OPERATING INSTRUCTION MANUAL



OPERATING INSTRUCTION MANUAL

for the

SIEMENS AERO-ENGINE

Sh 14A

SECTION ‘A’

PREPARATIONS FOR STARTING UP

1. Fill the oil tank with oil, but not right up to the edge. A space of 1 to 2 litres above the oil must be left for the recirculated oil x) which is returned to the tank from the oil sump by the recirculating pump when the engine is started. Before passing into the tank, the oil should be filtered through a close-meshed strainer. Keep all filling arrangements scrupulously clean.

2. Fill the petrol tank, placing a piece of clean wash-leather over the filling hole to act as a filter. After filling, carefully re-close both the oil and petrol tanks.

3. Oil the engine according to the instructions at Appendix ‘I’.

4. See that the following parts are secure, but without unduly loosening them:

a. The airscrew must be secured firmly to the hub and the latter securely to the shaft. The airscrew hub must be screwed tight and locked.

b. Oiling screws.

c. Connections of the ignition cables to the sparking plugs.

5. Test the carburettor gear to see that it works easily and properly.

6. Open both the petrol and oil cocks (if an oil cock is provided) and examine the connected feed pipes for leaks.

STARTING

A. Starting with Hand Magneto

1. Switch off the ignition.

2. Open the throttle, a little. The correct throttle opening facilities starting, but if the throttle is opened too far it cuts out the starting and idling arrangements on the carburettor.

3. Turn the engine through two or three complete revolutions and on each revolution pump in a charge of petrol using the petrol injection pump. When operating the pump, make the intake stroke slowly and the delivery stroke quickly. In cold or damp weather, two or three extra charges can be pumped in. Re-close the cock on the injection pump or cut off the flow of petrol through the pump.

4. On the report “airscrew released”, switch on the ignition (position M 1 + 2 on the switch, and in engines with double contact breaker also switch on the retarded ignition) and turn the magneto crank quickly until the engine starts. If the engine does not start, usually too much petrol has been injected. Cut off the ignition, turn the engine through several revolutions in the opposite direction to normal revolution, and again attempt to start up without injecting any more petrol.

If the engine again stops after a number of revolutions, the throttle is not open far enough or there is a shortage of petrol owing to choked jets, choked filters, or the idling jet is too small. In the latter cases the ignition must be cut off before attempting any adjustments.

B. Starting the Sh 14A engine with Compressed Air

1. Open the throttle to about a quarter.

2. Pump 3 or 4 (in cold weather 5 or 6) charges of petrol into the engine. Re-close the injection cock or cut off the petrol flow through the pump.

3. When the airscrew is released, switch on the ignition (retarded ignition with double contact breaker) and carefully open the cock on the compressed air cylinder. Then turn the magneto crank x) and slightly depress the check valve, when the engine will pick up.

4. Immediately the engine has started, re-close the compressed air cock.

If the same difficulties are experienced as already enumerated under a., then before any adjustments are made, close the compressed air cock and cut off the ignition.

Ground Test

After starting up the engine, allow it to run for about 4 minutes at a speed of 500 to 600 rpm. Note the oil pressure on the oil gauge. The speed of the engine may be gradually increased. In no circumstances must the oil pressure rise much above 4kgs per sq cm (60 psi), nor must it fall below 1.5 kg per sq.cm (20 psi), otherwise stop the engine immediately and determine the cause for this behaviour (“Engine Troubles” – Appendix ‘IV’).

Open the throttle quickly (but not too abruptly) to test the acceleration of the engine. A short spurt on full throttle will indicate if the engine touches top speed (2,200 rpm. A flight must not commence before the engine runs perfectly smoothly and satisfactorily on the ground. On the other hand, the engine should not be kept on full throttle for too long on the ground, the cooling action of the airscrew is insufficient for this.

To test the two ignition circuits, use the changeover switch to switch on each magneto separately. The resulting drop in speed should not be more than 30 rpm as compared with the speed on both magnetos. Should the drop be greater, this is due to sparking plug trouble, which is also indicated by the irregular noise of the exhaust.

In engines with electric ignition timers (with double breaks on the magnetos), test the running of the engine’s advanced ignition. Switch on the advanced ignition just before fully opening the throttle, but not later.

Flight Test

During flight, keep an eye on the revolution counter and the oil gauge. The maximum permissible speed of 2200 rpm must not be exceeded even in flying nose down or when diving.

The engine may suffer damage if the oil pressure drops below 1.5 kg per sq cm (20 psi).

Feed petrol to the engine from time to time when gliding so as to keep it warm and to prevent the sparking plugs fouling or becoming moist.

Standard Running Data:

Maximum speed of engine 2200 rpm

Speed in continuous flight, about 2050 rpm

Fuel pressure, kg. Per sq cm 0.1 to 0.3 (1.5-5 psi)

Oil pressure, kg per sq cm 2 to 4 (30-60 psi)

Oil temperature Max 65oC (150oF)

Temperature of cylinders 250oC measured at the rear plug (482oF)

After a Flight

After landing it is advisable to keep the engine running freely for several minutes (at a speed of about 500 rpm) and then to stop it by cutting off the ignition. When the engine has stopped, immediately close the petrol and oil cocks. After long flights, overhaul the engine as laid down in Appendix ‘II’.

Care of Engine

1. Keep the outside of the engine clean. Never use benzole or petrol for cleaning as these attack the paint on the light-metal parts. Paraffin may be used, but the best medium is one of the various liquid cleaners for engines on the market, applying and removing it with compressed air.

2. Keep all paint in good condition especially on engines used for flights at sea. Make good all damaged paint with thin coats of fresh paint.

3. As regards the care of the airscrew, follow the instructions of the makers. Note that the paint on wood airscrews is nearly always attacked by benzole, petrol or paraffin.

4. When the aircraft is left out in the open, cover the engine with a canvas hood.

5. On seasonal changes in weather: Change all oil (see remarks on summer and winter oil at Appendix ‘I’).

Supervision of Engine

General Examination as regards Running Conditions

1. The valve clearance should only be tested with the engine cold.

Remove a sparking plug from each cylinder.

Start the cylinder 1 and move the piston into top dead centre between the compression and the working strokes. (Note that both valves must remain closed. If not, turn the crankshaft through a complete revolution.) The clearance between the valve and the valve lifting roller is measure with a steel gauge, 0.2 mm thick. In old engines, it is advisable before adjusting the clearance of the inlet and exhaust valves to first determine that position of the cam plate giving the smallest lift of the valves (Between its four cams, the cam drum has four segments of the same height; after each two revolutions of the crankshaft, the next segment comes under the pusher roller.) The clearance is adjusted if necessary by means of the screw on the valve lever. After adjustment, carefully retighten the locknut.

After cylinder 1 has been tested, pass on to the cylinders 2, 3, 4 etc., in succession, each time turning the crankshaft through one revolution.

2. Airscrew. The airscrew hub should be firmly attached to the shaft, and the airscrew itself securely attached to the hub. The airscrew hut nut should be tightened and properly locked. The airscrew should run smoothly and steadily, which should be tested from time to time by means of impact plates.

With flanged hubs, the security of all nuts on the hub should be tested periodically when a new wood airscrew has been mounted on the hub, and if necessary tightened.

Also note the instructions at Appendix ‘III’ for taking down airscrews.

5. External Examination. All nuts on the outside of the engine should be securely tightened, and the locknuts on the housing, the cylinders and the engine fixing nuts must be properly secured. Test the cap nuts of all oil and fuel pipes to ee that they are tight, but without unduly loosening them.

Pistons and Connecting Rods

Remove encrusted oil from the bottom of the piston and polish the surface. Also remove carbonised oil from the piston ring grooves, taking care not to damage the grooves. The rings should move easily in their grooves. It is not always necessary to remove the piston.

By moving the main and auxiliary connecting rods up and down, see whether the bearings are still secure. The gudgeon pins should also be firm.

Test the piston rings in the cylinder and measure the clearance at the sides with a steel gauge. The clearance should not exceed 0.8 mm., otherwise put in new piston rings.

On reassembling the cylinders, liberally oil the liners with oil of the brand used in service and give the engine a turn or two.

APPENDIX ‘I’

Lubricating Instructions

1. Before each flight : Examine the oil level. (Refer Preparations for Starting Up on page 2).

2. After 5 hours flying or in longer flights before each start : Oil the sockets on the pusher rods. To do this press the valve springs together and remove the pusher rods.

Lubricant : Graphite grease or vaseline with 10 percent graphite added or Shell valve rocker grease. See that the pusher rods are not interchanged on replacement.

Grease the needle bearings of the valve levers. As lubricant use hot-bearing grease or clear viscous mineral oil or Shell valve rocker grease, but not ordinary yellow Stauffer grease, which contains diluents such as lime, soap etc.

Lubricate each joint of the control gear with a drop of oil.

Screw off the oil drain plug from the oil sump and run off water condensate.

3. After 25 hours’ flying : Empty the oil in the tank and the oil sump. Clean the oil strainer in the oil sump and the oil filter in the oil feed pipe. After replenishing with clean oil, see that the oil feed pipe between the oil pump and the tank is filled throughout with oil and does not contain any air locks. To make this inspection, remove the pipe at the oil pump and see if the oil issues without bubbling. Refix the oil pipe.

Clean the petrol filter and strainer in the carburettor.

Rinse the strainers in the engine exhaust with petrol if choked with oil.

4. After several months’ idleness: Renew all oil (as per 3. above).

APPENDIX ‘II’

Examination of Engine after Long Flights

This examination should be made before the engine cools.

1. Temperature of cylinders. The cylinders should be at a uniform temperature overall. If there is a local overheating near the sparking plugs or the compressed air valves, examine these parts and see whether they are securely fixed. Over-heated cylinders must be replaced together with their pistons and the conditions of the liners carefully examined.

2. Examine the fuel, intake and oil pipes for leaks.

3. Compression. From each cylinder remove one sparking plug, except from the cylinder whose compression is to be tested.

4. Full-Throttle test on the ground (only for a short period). In this test the rated speed on full throttle on the ground must be obtained (See Page 2). If this speed is not obtained, locate the source of trouble as outlined in the instructions in Appendix ‘IV’ provided that the lack of power is not due to unusual weather conditions (very low barometric pressure, very high air temperature or very high atmosphere humidity).

c. Periodical Examination

1. After every 30 to 50 hours of flying, examine the following:

Packings on the intake pipes, for which purpose remove the flanges on the intake pipes at the intake ports.

Contact Breaker. Remove the contact breaker cover, separate the contacts, and, if necessary, clean with a fine flat file. If desired, special files for cleaning contacts can be supplied. Emery cloth or emery paper must not be used for cleaning the contacts as they are fibrous.

Revolve the engine until the contacts are completely apart. The contact gap should not exceed 0.3 to 0.4 mm and should be checked each time the contacts are cleaned; if necessary, readjust the clearance by means of the contact screws. Carefully retighten the locknut on each contact screw after adjustment.

If after long use the contacts become so worn that they can no longer be accurately adjusted, put in new contacts. This is best done by the firm supplying the magneto.

Take particular care that no oil gets on to the make and break contacts, as combustion of the oil causes the contacts to wear prematurely. The magneto is then also liable to work irregularly, as oil is a non-conductor.

Sparking Plugs. Test the gap between the electrodes, which should be 0.4 mm. If a sparking plug tester is available the plugs should be tested under pressure (about 6 kg per sq cm).

Compressed Air Unit (in engines with a compressed air starter). Examine the check valve on the cylinder and if necessary regrind the valve cone. At the same time, check the tension of the valve spring.

2. After every 100 to 150 hours flying, according to the demand placed on the engine and the characteristics of the fuel used, the engine should be submitted to a partial overhaul, which may be limited to an examination of the cylinders and can be done without removing the engine from the fuselage. It is imperative that this examination be carried out in a place where the engine is exposed to as little dust as possible, and all openings in the crankcase after removing the cylinders, covers etc., must also be carefully covered to exclude dirt. All dismantled units should be laid out systematically in the order they are taken down, so as to ensure that on reassembly all parts are replaced in their proper positions.

For instructions regarding the systematic dismantling and reassembly of the engine, see SECTION ‘B’ - General Overhaul.

Take down the cylinders after removing the pusher rods and intake pipes.

Thoroughly decarbonise the combustion chamber and examine whether the cylinder walls have become scored.

Valve seatings and valve cone seatings should be clean, if not, regrind the valve. Only slightly mill the valve seatings and grind to obtain a smooth and close fit.

The valve stem should not have too much play in the valve guide. If necessary, change the valve guide.

APPENDIX ‘III’

Removal from Fuselage

Drain all oil from the engine.

After removing the nut-locking devices and hub nut[1](1), take off the airscrew hub1(2). The extractor head of the hub extractor for Siemens bolted hubs has a right-handed thread for screwing in, and that of the extractor for Rupp and metal-airscrew hubs a left-handed screw. Also metal-airscrew hubs must always be removed with a special extractor and not by merely loosening the main hub nut; otherwise the parts may be damaged as well as the crankshaft. The extractor for metal-airscrew hubs is made up of a threaded ring and the extractor for Rupp hubbs.

Remove exhaust manifold, carburettor gear, petrol pipes, petrol pump, carburettor, carburettor manifold and oil pipes, and break all connections to instruments and auxiliary gear. Remove vent pipe.

Place lifting gear on engine so that total weight of engine is borne by ropes along round cylinders 2 and 7. Loosen nut to lift engine.

APPENDIX ‘IV’

ENGINE TROUBLES

Choice of Airscrew

Principal Consideration : The airscrew should be of such dimensions that in horizontal flight, on full throttle near the ground, the maximum permissible speed of the engine is not exceeded. The speed is 2200 rpm.

Before testing the airscrew in flight, a test run should be made on the ground. It is, however, usually not sufficient to test the airscrew it is proposed to use merely on the test bench or in a stationary aircraft, in order to arrive at its performance with the engine on full throttle. For on full throttle, an engine runs at a higher speed in actual fight than on the ground using the same airscrew, since the speed of the engine and airscrew increase by about 100 to 150 rpm. Out of consideration of the running conditions (taking off power) as well as to nurse the engine (preventing excessive speeds when flying downward on open throttle), it is desirable that this increase in airscrew speed has been accurately determined in a test run on the ground alone sufficient.

On the other hand, the speed of the airscrew in horizontal fight and on full throttle must not drop much below the rated speed of 2200 rpm. There is a tendency to use heavy airscrews, ie airscrews requiring considerable power to drive and which have a comparatively low maximum speed, so as to definitely avoid the maximum permissible speed of the engine as intended, but on the other hand places a heavier average load on the engine. At the same time, the take off power of the engine is unnecessarily reduced, which may be dangerous where the taking off conditions are not favourable. In consequence, an airscrew should not be used which is horizontal flight on full throttle near the ground revolves at a speed more than 100 rpm lower than the prescribed maximum speed of 2200 rpm.

For safe flying it is essential to have a well-balanced airscrew which will run smoothly and uniformly, and which is mounted absolutely securely on the airscrew hub.

APPENDIX ‘V’

Choice of Fuel and Oil

The principal considerations in choosing a fuel are:

Only use petrol and oil of the very best quality. Remember that if this fundamental rule is not followed the engine must suffer and flying become dangerous. The smallest saving in fuel and oil costs is liable to lead to trouble and to damage to the engine if the anti-knock value of the petrol is too low, the lubricating oil too think or of unsatisfactory quality. There is also a serious danger in using inferior petrol since the sparking plugs may cause trouble, the valves and the exhaust ports become choked and the carburettor fouled.

A. Fuel

Flight petrol should satisfy the following requirements:

1. High anti-knock value

2. High volatility

3. Unaffected by temperature changes, eg on changes in altitude

4. Exercise no corrosive action on metals; and

5. Contain no dissolved or suspended impurities.

[pic]

The specific gravity of a petrol is no indication of its quality and no criterion of its suitability under specific working conditions.

The anti-knock value can only be determined acoustically by an experienced engineer, and it is advisable to make two test flights, one using the petrol under test and the second with a standard petrol of known anti-knock value, eg 60 : 40 percent petrol-benzole mixture, and to compare the performances of the engine, ie the maximum speeds obtained. For the high compression (6.2 : 1) Sh 14A engine, only a mixture of petrol and benzole containing at least 30 percent benzole or a fuel with similar anti-knock rating should be used.

In standard engines with a compression ratio of 5.2 : 1, plain flight petrol will be found quite satisfactory, but the volatility curve of the petrol should conform as close as possible to the curve shown in the figure above.

Difficulties in the running of the engine are usually not due to the low boiling point of the petrol, but to those of high boiling point. These condense in the intake pipes and even in the cylinders when the engine is running light or in gliding, and from their chemical composition cause the engine to knock. It is essential therefore for the whole of the petrol to vaporise without residue at a temperature not exceeding 170oC. Too low a proportion of low boiling point fractions (less than 10 percent volatilising at 75 oC) may make starting up difficult.

Apart from visible impurities which can be largely removed by suitable precautions when filling the tanks and by carefully keeping the petrol filter clean, the petrol should also contain no impurities in the form of dissolved resins, etc. These form films in the intake pipes and in the cylinders and may readily interfere with the functioning of the valves and cause leaks at the valve seatings.

Water in the petrol, not only as free drops, but also in the dissolved state, is also an impurity. Petrol has the lowest solvent action on water, while benzole can dissolve a larger volume of water. The solubility of water in alcohol is higher still. The corrosive action of the fuels on metals is in the same order, alcohol being the most corrosive.

These points should place the use on his guard against new brands of petrol, which he has not thoroughly tested.

It should not be overlooked that when changing from one type of fuel to another, eg substituting a petrol-benzole mixture for plain petrol, readjustment of the carburettor is necessary. A large proportion of benzole in a spirit requires a lower rate of supply, and hence narrower fuel jets.

B. Lubricating Oil

Only good grade mineral oils should be used for the circulating oil system in these engines. Under normal conditions of temperature, with the lowest night temperature never under zero, the lubricating oil should satisfy the following requirements:

Specific gravity at 15 oC 0.89 to 0.91 kg./1

Flash point in open crucible About 185 oC

Viscosity at 50 oC About 15 oC

Viscosity at 100 oC 2.6 to 2.9 oC

Loss after 2 hrs. heating at 100 oC, not exceeding 0.4 percent

Ash content, not exceeding 0.05 percent

Acid content, not exceeding 0.07 percent

It is quite useless to judge an oil from its viscosity at the storeroom temperature, as such tests often make very suitable oils appear useless. In fact, a low viscosity at ordinary outdoor temperatures is desirable to facilitate the starting of the engine and to start-up the oil circulation system quickly.

When frost is likely to be encountered, oils capable of withstanding low temperatures should be used. These should satisfy the requirements enumerated above and also have a congealing point of between –12 and –16 oC.

Apart from a determination of the above-mentioned values, an exhaustive examination of an oil in the laboratory to determine its exact behaviour under all service conditions can hardly be carried out. It is advisable therefore to reject all known brands of oil and to use only approved and reliable brands. The makers of the engine are prepared to place at the disposal of users their own practical experience with any particular brand of oil.

Never make any admixture to a lubricating oil.

Only a few points of the engine are not lubricated by the circulation system and thus require lubrication by hand. These include the needle bearings of the valve levers, and the sockets of the pusher rods. Further instructions regarding this point are given at Appendix ‘I’.

SECTION ‘B’

GENERAL OVERHAUL

General Instructions

The taking-down and re-assembly of the engine requires great care, considerable skill and a proper understanding of the relationship between the various parts. Incorrect handling of tools, applying unnecessary force and careless work may lead to serious damage to the engine.

All parts which have been run in should be laid out in systematic order when dismantling the engine so that they can be replaced in exactly the same relative positions.

No part of the engine can be dispensed with, not even the most unimportant. Every nut-locking device and every spring ring must be correctly replaced on re-assembling the engine. Any omission may have fatal consequences. Cotters, safety wires and all light spring rings and guard washers must not be used a second time, but immediately on dismantling the engine should be rendered useless. Nuts, discs, fixing screws, etc should, as far as possible, be replaced in their original positions in order to preserve uniformity.

The engine should be taken down in a clean workshop free from dust. Before starting work, procure a wooden stand, about 0.65 m high with a stout round top about 0.65 m. in diameter, and from it cut out a section of the dimensions shown in the sketch overleaf to take the rear of the crankcase. Also provide a sufficient number of boxes in which to keep the parts separate as they are removed.

[pic]

Dimensions of hole required in engine stand.

I – Removing and Dismantling the Engine

a. Removal from Fuselage

Drain all oil from the engine.

After removing the nut-locking devices and hub nut take off the airscrew hub. The extractor head of the hub extractor for Siemens bolted hubs has a right-handed thread for screwing in, and that of the extractor for Rupp and metal-airscrew hubs a left-handed screw. Also metal-airscrew hubs must always be removed with a special extractor and not by merely loosening the main hub nut otherwise the parts may be damaged as well as the crankshaft. The extractor for metal-airscrew hubs is made up of a threaded ring and the extractor for Rupp hubs.

Remove exhaust manifold, carburettor gear, petrol pipes, petrol pump, carburettor, carburettor manifold and oil pipes, and break all connections to instruments and auxiliary gear. Remove vent pipe.

Place lifting gear on engine so that total weight of engine is borne by ropes slung around cylinders 2 and 7. Loosen nut to lift engine.

b. Dismantling the Engine

While the engine is slung from the lifting gear, remove the distributor disc on the magneto, leaving the cables attached to the disc. Remove tension strips and take off the magneto. Detach the cables from the sparking plugs. Unscrew choke conduit and remove with cables and distributor discs.

[pic]

Extracting the airscrew hub.

Place the engine on the stand with the butt of the crankshaft at the bottom.

[pic]

Remove rear engine cover.

Remove the compressed air distributor manifold between the distributor and the cylinders.

Take off the nuts on the rear crankcase cover and remove the rear cover together with all attached shafts and components using the extractor (2) or with the fixing plate.

[pic]

Extracting double gearwheel from rear of crankshaft.

Unscrew the ring nut at the crankshaft rear half and draw off the double driving wheel driving the magnetos and the oil pump.

Take down the intake pipes. Just loosen the rear nuts (now at the top) on the cylinder flange after straightening the locking washers, but do not remove the nuts altogether.

A special spanner is provided for undoing the nuts on the cylinder flanges near the oil sump.

Turn the engine over.

[pic]

Withdrawing front crankcase cover.

Remove the sparking plugs. By turning the crankshaft, relieve the valve springs as much as possible and remove the pusher rods by depressing the valve levers.

Recover the cover. Screw off the nuts on the front crankcase cover and loosen the ring nut on the crankshaft after straightening the locking washer; take off the front cover. Loosen the tappet guides by light taps from the inside using a punch; remove the tappets.

Without removing the main reduction gear wheel, remove the cotters on the three castle nuts on the bearing shield and unscrew the nuts; then take down the reduction gear as a whole. This procedure prevents the needle bearing falling out in dismantling the reduction gear.

[pic]

Extracting valve gear driving wheel and driving sleeve.

In no circumstances should the reduction gear shaft and the main reduction gear wheel be taken down by striking downward on the reduction gear wheel, as some damage is sure to be done to one part of another.

Fix the extractor with the grip behind the union of the driving sleeve and withdraw the sleeve together with the valve gear driving gear wheel. Close all apertures in the wall of the crankcase with corks, and take off the cam disc. Collect together the various parts of the needle bearing which then fall to pieces; there are 134 needles. The needle bearing bush and the inner race of the front roller bearing remain on the crankshaft.

Take off the cylinders: Unscrew all nuts on the cylinder flanges where this has not already been done, but do not remove the nuts yet. Do not start taking off all cylinders at the same time, but deal with them one at a time, leaving cylinder No. 5 (the cylinder with the main master connecting rod) the last on the crankcase.

[pic]

Pressing out the gudgeon pin.

By turning the crankshaft, bring the pistons into roughly top dead centre. Withdraw the cylinders, if necessary turning them slightly to and fro. Never insert a tool under the cylinder flanges. When each flange has been listed slightly, so that the cylinder can be easily lifted off, remove the cylinder holding nuts. Do not allow the connecting rods to strike against the crankcase. Carefully stand the cylinders where they are protected against damage and dirt immediately after removing each cylinder.

Take down the corresponding piston: First remove the top spring ring with the spring ring lifter, leaving the lower one in the piston cye. To prevent scoring when pushing out the gudgeon pin, it is advisable to warm the piston to about 80 to 100oC (by immersing in hot oil or placing heated by not red-hot metal plates in conact with the piston head, or in exceptional cases where there is no danger of fire or explosion, by going over the piston head with a small soot free gas or alcohol flame). Remove the gudgeon pin using the proper tool provided; do not use a hammer, which might damage the connecting rod bearing.

Loosen the nuts on the crankcase bolts. Knock out downwards and withdraw all bolts on the crankcase, except two on opposite sides of a diameter.

The front of the crankcase can then be lifted off and the crankshaft withdrawn from its rear bearing.

c. Dismantling Cylinders and Crankshaft Gear

For further dismantling the cylinders, a cylindrical wood block mounted on a baseboard is required of the dimensions shown in the sketch below. The cylinders are placed on this block in turn, the valves resting on the curved head.

[pic]

Wooden block for dismantling cylinders.

Compress the valve springs using the spring lifter, which is applied to the raised valve lever, and withdraw the locking pieces. The valve is then released.

To dismantle the crankshaft, it is first necessary to remove the roller bearings from the crankshaft.

The needle-bearing bush is removed together with the front roller bearing.

Secure the crankshaft firmly in a vice, gripping the front crank web. Remove the locknut on the ring nut on the crankpin holding bolt and slightly loosen the ring nut, [pic]

Taking down the valves.

but do not remove same. Take the crankshaft out of the vice; place it on the bench and screw off the nut, when the whole crankshaft will come apart into its three main units (front section, crankpin and maneton). The two thin copper washers should be immediately destroyed; as in no circumstances must they be used a second time.

Before knocking out the wrist pins of the auxiliary connecting rods, remove the fixing screws on the locking discs and knock the tight-fitting discs with the copper punch.

[pic]

Withdrawing roller bearings from crankshaft.

The compressed air distributor and the oil pump on the rear crankcase cover can be readily taken down without special tools. But take great care to avoid taking to pieces the regulating valve on the oil pump, as its correct adjustment requires experience and special testing gear or must be determined from observations during flight.

[pic]

Dismantling the crankshaft.

II – TESTING OF COMPONENTS AND REPAIRS

The various components of the engine must be examined for overall wear as well as the conditions of running surfaces carefully inspected. The teeth on all gears should be in good condition and all surfaces in running contact should be smooth and free from scratches and grooves; ball and roller bearings should have no noticeable radial play and the races should be in good condition and not loose. If there is any doubt of the advisability of using any component a second time, it should be sent to the makers, if necessary together with its associated components for testing the clearance, fit, play etc.

The cylinder liners must not be scored. Decarbonise the cylinder heads as thoroughly as possible, which may be considerably facilitated by letting them stand in benzole overnight. Remove the carbon deposits with a scraper, but not with sharp-pointed tools. Be careful not to damage the valve seatings. It is absolutely essential to remove completely all spongy, cracked and flaky deposits, as these readily produce premature ignition. On the other hand, do not attempt to remove the lower smooth layer of carbonised oil, which is usually well burnt into the surface and is very hard.

After decarbonising, rinse out the inside of the cylinder with petrol and grind in the valves. Note carefully that the valves and cylinders are numbered and each valve should be ground to fit its proper cylinder. A special plate should be used for securing the cylinders in the vice. Never fix a cylinder in the vice by means of the flange.

Always obtain a close fit on the valve seatings by grinding them in and not by milling. Only when a valve has an uneven seat or the valve seating or valve cone is pitted and cannot be smoothed by grinding, should the valve seat be lightly milled with the appropriate valve seat-milling cutter. To determine whether a valve gives a close fit right round its seating, take off a very find shaving with the milling cutter. If the cuter has only “gripped” on one side, this indicates slight unevenness of the valve seat or of the surrounding part of the cylinder head. In this case, mill the surface until the new seat is about 2mm wide on the narrower side. Inequality in the width of the seat, as well as the widening produced when a seat is re-milled to remove pitting, may be readily removed again by means of two special milling tools. These are the special type cutter that mills the spherical inner surface of the cylinder head, and the slightly tapered cutter, which cuts the edge between the seat and the admission or exhaust port. After milling, the seat should have a uniform width of 2 mm. Using these two special cutters prevents too much metal being removed in order to obtain the narrow width of the valve seating required.

On grinding in the valve, a close fit is indicated by a suction action between the valve cone and the valve seating. After cleaning the chamfered valve seat, a uniform grey line not more than 2.5 mm wide should be visible on the seat. This is the final criterion that the valve seat is of the correct width.

Damaged valve guides can be removed with a special extractor. Heat the cylinder to about 150 to 200oC in a furnace (careful supervision of the temperature is necessary) or in an oil bath. Drive in new valve guides with light tape and after the cylinder cools smooth with a special reamer and, if necessary, mill the valve seat.

Remove the piston rings with the pistons. The pistons heads must not be cracked, not the liners pitted or scored, nor the piston ring grooves damaged in any way, nor must the pistons be excessively carbonised at the sides. Carefully decarbonise the piston head and piston ring grooves (do not damage the grooves), and well polish the piston head. Also clear the oil holes in the grooves from any accumulated combustion residues. The piston rings should move easily in the grooves.

The cylinder must be reground and the piston changed if wear has increased the diameter of the bore by more than about 0.15 mm as compared with the standard diameter. Regrinding should, if possible, be done by the engine makers to ensure a clean and accurate job. When regrinding, note the following standard dimensions:

Bore of cylinder Oversize

Standard cylinder 108 + 0.015 mm 0.0 mm

K2 cylinder 108.2 + 0.015 mm 0.2 mm

K4 cylinder 108.4 + 0.015 mm 0.4 mm

K6 cylinder 108.6 + 0.015 mm 0.6 mm

Marking on pistons (stamped either next to gudgeon pin hole or below bolt eye, on airscrew side) and on cylinders (stamped on flange):

N, K2, K4, K6

Markings on piston rings and oil wiper rings (engraved on wide surface of ring):

Standard ring, no dot; K2 rings, 2 dots; K4 rings, 4 dots; K6 rings, 6 dots.

(Number and letters on the piston rings denote the material and the supplier of same.)

Piston rings and oil wiper rings when fixed in the cylinders should not have more than 0.8 mm lateral clearance.

When replacing used bearing bushes on the connecting rods, note the following:

Wear of the master connecting rod bush is nearly always associated with corresponding wear of the crankpin which must be carefully reground, polished and rubbed with a soft cloth. As this work requires considerable skill and special tools, it is strongly recommended that the work be entrusted to the makers of the engine; at the same time a spare bush can also be finished to the correct dimensions.

The same applies to the bronze bushes on the connecting rods. These must not only be absolutely round, to the correct dimensions and perfectly smooth, but their area must also be exactly parallel to each other. It is advisable therefore to leave the changing of these bushes also to the makers, especially as they employ a special treatment for hardening and polishing the inner surfaces of the bushes.

Although the crankpins of the Sh 14A engine can be replaced, this should only be done by the aero-engine makers or by special fitters, which have been specially trained by these works.

Oil leads and chambers in the crankshaft should be cleaned from any deposits of circulating oil by thorough spraying with petrol or benzole. These places on the Sh 14A shaft area readily accessible after taking down the shaft.

Test the rigidity of the auxiliary gear on its seating.

The dismantling of the auxiliary drive gear in the Sh 14A engine, if necessary, is carried out as shown in the illustration below. Liberally grease the thrust screw and auxiliary drive wheel at their points of contact.

[pic]

Dismantling Auxiliary drive gear.

Examine the crankcase to see that all stud bolts are firm. Clean packing surfaces, if necessary, taking care not to damage them. Carefully wash out all oil deposits.

III – RE-ASSEMBLING THE ENGINE

All parts, which are rigidly connected, eg the gears on the crankshafts, should be treated with tallow or graphite grease before replacement, as well as the threads of the ring nuts.

[pic]

Driving in the wrist pins with the double punch.

The only parts not requiring attention are those, which are lubricated by the circulating oil system, eg the gudgeon pins and these only require oiling on re-assembling. All parts with working surfaces must be washed with petrol before replacement, and liberally oiled with the same lubricant (not with grease) as is used in flying.

Cylinders, pistons, connecting rods, gudgeon and wrist pins and most units of the control gear are marked with stamped or engraved numbers. These numbers should be followed when re-assembling the engine in order that each unit is replaced in its original relative position. If new parts are put in which bear no markings, these should be marked no later than at the time of replacement in exactly the same way as the parts they replace.

In German territory, an engine after being taken down completely can only be re-assembled under the supervision of a testing official of the National Safe Flying Department. Similar regulations are in force in most other countries.

A. Re-assembling the Cylinders and Crankshaft Gear

In re-assembling the cylinders, do not forget the spring rings on the valve spindles. Grease the valve springs.

The re-assembly of the crankshaft gear commences with putting together the master connecting rod and the auxiliary connecting rods. Place the wrist pins on the double punch and push the locking disc into the wrist pin slots, then drive in the wrist pins with light taps. Secure the locking discs with screws and secure the latter with a common safety wire (soft annealed iron wire is suitable for this purpose).

To re-assemble the crankshaft, secure the front section of the shaft in the vice as shown in the illustration below. Push through the holding bolt – the contacting surfaces between the holding bolt and the crankshaft front section should be perfectly smooth and clean – and fit a new copper washer. Place the crankpin in position so that the cipher marked on the radial teeth is at the rear and the top.

[pic]

Re-assembling the crankshaft gear

Fix on the connecting rod assembly, taking care that the lock discs on the master connecting rod head are at the back. Place on the second packing ring and replace the maneton – its position relative to the crankpin is indicated by three ciphers; screw on the holding bolt nut. This nut should be tightened so that the mark on the nut shown in the attached illustration is in line with the middle notch of the crankshaft locking strip.

Fix the lock device and bend it over against the square head of the holding screw. [pic]

Position of tightened holding bolt nut.

Grease the seatings on the roller bearings and place the shoulder rings for the roller bearings in position. After heating to 80 to 100oC push the bearings on to the shaft.

After re-assembling, the crankshaft must be tested in a revolution-testing stand for correct alignment and truth. The permissible error in alignment is 0.05 mm for both the front and rear sections of the shaft.

B. Final Assembly of Engine

Place the crankcase rear housing on the engine stand; push the crankshaft into its bearing and arrange the connecting rods in position. The master connecting rod belongs to cylinder No 5. Place the crankcase front cover in position and put in the housing bolts. No paper packing must be inserted between the crankcase front and rear sections. Tighten the nuts on the belts.

Mount the pistons in position. Begin with piston No 5, ie with the piston belonging to the master connecting rod. The bolt eye of the piston, which is marked at the bolthole or on the inside of the piston, must be on the airscrew side. Heat the piston to about 150oC on a hot plate or preferably in an oil bath and place in position on the connecting rod head. Insert the gudgeon pin after oiling liberally. If the piston is at the right temperature, the gudgeon pin can be inserted by hand (this is a criterion that the piston is at the right temperature). Fix spring ring to lock gudgeon pin, in such a position that the beginning of the ring is about 5 mm to the side of the groove in the piston eye. Fix the piston rings in their correct positions (see sketch) and well oil the pistons. Regarding the arrangement of the oil wiper rings, additional instructions are required.

[pic]

Mounting of piston rings

1,2,3 Piston rings 4 Oil wiper rings

The sketch above shows the numbers and positions of the piston rings in a brand-new engine straight from the works. If after running-in the oil consumption of the engine has appreciably increased, cylinders 3, 4 and 6 should each be provided with two oil wiper rings as shown in the illustration below. The top cylinders which, by virtue of their positions, do not have an excessive oil consumption and cylinder No 5 which being the cylinder working on the master connecting rod requires more liberal oil supply, are in the first instance not altered in this way.

[pic]

Mounting of piston rings

1 & 2 Piston rings 3 & 4 Oil wiper rings

If the oil consumption is still high after making these alterations in the piston rings, and if the engine works efficiently in all other respects – correct oil pressure, sufficient density of oil, medium cylinder temperatures, good brand of lubricant is used – then two oil wiper rings can be fitted to all cylinders. After re-assembling each piston, replace the corresponding cylinder. Insert the paper packing and cover the cylinder liners with a liberal film of oil. Compress the piston rings with the special clip and carefully push the cylinder over the piston and secure it to the crankcase.

Slightly warm the needle-bearing bush and drive it onto the crankshaft. Cover the bush with a layer of Vaseline and embed the needles close together. The needles must be arranged in two groups of 67 needles each and separated by the spacing ring. Best order of working : Insert lower group of needles, slip on cam disc, insert spacing ring and then the upper group of needles.

Replace the auxiliary drive gear. First drive the driver sleeve (after inserting the key) and the auxiliary gear driver wheel on the crankshaft. The relative position of these parts is indicated by ciphers. Fix on the complete auxiliary drive gear by the flange; the marked teeth on the cam disc toothed crown and on the small auxiliary gear drive wheel, as well as on the main auxiliary gear drive wheel and valve gear driving wheel (see sketch) must be in proper engagement. To avoid mistakes, make these teeth more conspicuous by marking them with chalk.

[pic]

Sketch showing engagement of auxiliary gear and valve gear driving wheels.

Mount tappet guides with tappets. Insert tappet rods (the front tappets operate the admission valves and the rear tappets the exhaust valves). Adjust the valve lift, starting with cylinder No 1. To make this adjustment, the piston in the cylinder being adjusted should be towards the end of the compression stroke. This position is obtained when both valves are closed and the wide groove on the corrugated teeth point to this cylinder. The valve lift is 0.2 mm for both the admission and exhaust valves, measured on the cold engine between the valve lifting roller and the valve or between the tappet and the ball head. A steel gauge of suitable thickness is used for testing the lift.

In the case of engines, which have been in use for some time, it is advisable before adjusting the lift of the admission and exhaust valves to find the segment of the cam disc giving the smallest valve lift. (Between its four cams, the cam disc has four segments of the same height; after every two revolutions of the crankshaft the next segment comes under the tappet roller.) After making this adjustment on cylinder No 1, repeat the same procedure on cylinders Nos 2, 3, 4 etc., turning the crankshaft through a complete revolution on passing from one cylinder to the next. To test the valve timing and also to adjust the valve gear when the positioning marks on the gear wheels are not distinguishable, proceed as follows: Adjust the valve lift on cylinder No 1 t 0.8 mm (this has been found by experience to be the lift when the engine is warm and the cylinders have expanded). Fix the crank spanner with adjustment pointer indicator on the crankshaft and lay strips of paper between the valve lifting roller and the valve. The following letters are stamped on the crankcase:

• E.o. (admission valve opens,

• B.s. (admission valve closes),

• A.o. (exhaust valve opens); and

• A.s. (exhaust valve closes) (see sketch).

Slowly turn the crankshaft in the normal direction of revolution. When the paper strips have become clamped tightly at either the admission or exhaust valve of cylinder No 1, the adjustment indicator should point to E.o. or A.o. respectively; immediately the paper is released, the pointer should indicate either E.s. or A.s. according to the valve tested.

If there is a marked difference between the indications or the pointer and the markings, disengage the valve gear driving wheel and displace the main auxiliary drive wheel backwards or forwards by one tooth, and then re-engage the ……?.. Again test the timing. Note that tests of this adjustment will only be accurate if the valve lift is exactly 0.8 mm and the adjustment pointer is not bent.

After these tests, readjust the valve lift on cylinder No 1 to 0.2 mm.

Place the crankcase front cover in position, remembering the paper packing. Push on the splash disc with the raised flange to the outside, and also the ring nut guard; then screw on the ring nut. Tighten the nuts on the crankcase front cover. Screw the sparking plugs and compressed air check valves into the cylinders. Carefully tighten the ring nut on the crankshaft front part and lock it. Fix on brass ring 1108 and the cap.

[pic]

Intermediate rings on front of engine.

Turn the engine over.

Push the double gear wheel on to the magneto shaft, after inserting the corresponding key. Tighten the ring nut and secure with spring ring.

Fix the mounting ring, tighten the bolt nuts and lock them. Put the paper packing in position and secure the crankcase rear cover.

Replace the intake pipes; use good packing on both sides of the joints. Fix the compressed air feed pipe between the fixing plate and the cylinders. A shorter pipe is provided for cylinder No 5, the sparking plugs being here directly side-by-side.

Sling the engine from the pulley with the crankshaft horizontal.

In adjusting the ignition which now follows, again start with cylinder No 1 (as in adjusting the valve gear), corresponding to which the mark VZ is stamped on the crankcase. The distributor blocks of the magnetos have already been removed.

[pic]

Fine adjustment coupling and magneto

The advanced ignition must be very accurately adjusted as in flight the engine runs almost exclusively on advanced spark. Any variations in the adjustment range of the timer are therefore of no moment, as they only slightly displace the retarded ignition.

1. Take a sparking plug out of each cylinder, so as to allow the engine to be turned easily by hand.

2. Fix the crank spanner with adjustment pointer on the crankshaft. Keeping an eye on the valves of cylinder No 1, move the crankshaft to roughly top dead centre (adjustment pointer points to the top). Both valves should then be closed, if not, turn the crankshaft through another revolution.

3. Turn the crankshaft exactly into the position corresponding to advanced ignition (pointer should read VZ).

4. a. In magnetos with automatic timers : Magneto JF7 rotates in a clockwise direction, so that the letter R on the distributor wheel corresponds to it. Place the magneto on the magneto bracket with the driving end facing the engine. Note the correct direction of rotation of the magneto (opposite to that of the crankshaft, see arrow in picture).

By holding the driving wheel stationary and turning the distributor wheel to the right, the automatic timer can be turned as far as the stop, the magneto then being in the advanced ignition setting.

Turn the driving wheel of the magneto (in the proper direction) until the letter R on the distributor wheel is about 2 to 3 cm in front of the mark on the distributor housing. Then lightly brake the driving wheel and continue to rotate the distributor wheel slowly, until the letter R and the mark on the housing coincide.

The timer then strikes the stop and the magneto is adjusted to the advanced ignition setting when these two marks coincide.

b. In magnetos with double contact breakers:

By turning the driving shaft of the magneto in the direction of the arrow, the letter R on the distributor wheel and the line engraved on the housing are brought to coincide.

c. In magnetos with snap couplings:

Adjustment is made in the same way as described in 4b. with the difference that the magneto must be rotated in a direction opposite to its normal revolution so that the snap coupling does not “snap home”.

5. When adjusted, push the magneto forward into position and couple it with the engine.

To test the operation of the magneto, check the magneto breaker points for proper gap. Place a piece of strip steel about 0.03 mm thick between the breaker points. Get an assistant to turn the crankshaft slowly in the right direction (anti-clockwise looking from the butt of the shaft).

In magnetos with automatic timers: Keeping an eye on the contacts, hold the distributor wheel in the advanced ignition position (touching the stop on the right). When the strip of steel can be easily pulled out, the adjustment indicator should read VZ. (Small deviations can be neglected, but can be easily corrected with the fine adjustment coupling.)

Again check that the moment the contacts open both valves on cylinders No 1 are closed.

In magnetos with double contact breakers: Determine the timing of that contact breaker which opens first and compare the position of the crankshaft as described above.

In magnetos with snap coupling: In these types of magneto the sparking cannot be tested by continuous rotation of the crankshaft in the normal direction. On the other hand, turn the engine and with it the magneto until the snap coupling is disengaged (a metallic click is heard). Immediately this happens the crankshaft is rotated backwards through about 20o, ie in a direction opposite to the normal working direction. The magneto points are now checked for proper gap in exactly the same way as with magnetos without snap coupling.

Replace all sparking plugs, which have been removed for these tests and screw them well home. Attach the cable conduit to the engine and the cables to the plugs. Attach the cable holder; the connections of the cables to the distributor block of the magneto should not be touched on dismantling the engine (as already advised in the instructions for dismantling). Should, however, the cables have been disconnected, note that looking for the airscrew side the h.t. cables of the front group of plugs are connected to the left-hand magneto and the rear group of plugs to the right-hand magneto. The h.t. cables of No 1 cylinder are connected to terminal 1 of the corresponding magneto; other connections to the engine are made in the firing sequences: 3 5 7 2 4 6 and to the distributor block to terminal 1 in the order of the stamped numbers.

The compressed air distributor must now be adjusted. Move piston 1 to the end of the compression stroke. Looking down on the distributor housing. The distributor rotates in a clockwise direction. Individual connections to the distributor are indicated by the numbers of the corresponding cylinders. Thus port 1 belongs to cylinder No 1, port 2 to cylinder No 2, and so on. On fixing the distributor cover, port 1 must be at the top.

Put in the distributor shaft and the spring. Fix in position the distributor disc with driver and then the distributor cover, such that port 1 of the cover is the next port to be uncovered by the slot in the distribution disc, while port 6 is opposite the slot and completely uncovered. The leading edge of the slot should be about 2 mm from port 1 in the cover. This adjustment is readily made by removing the cover and distributor disc and readjusting the driver on the fine adjusting teeth several times.

Secure the cover and attach the distributor pipe between the distributor and the mounting ring plate, starting with the shortest pipe.

c. Re-fixing the Engine in the Fuselage

Replace the engine in the fuselage of the aircraft using appropriate lifting tackle; avoid applying undue force; tighten the engine holding nuts and lock them.

Fix the carburettor intermediate unit, carburettor, carburettor gear, petrol pump, fuel feed pipes, oil pump and oil pipes (except the fresh oil supply pipe) and carefully test all joints for leaks. Fill the oil tank, and allow oil to flow through the make-up oil feed pipe until no further bubbles appear; then join up this pipe.

Attach the exhaust manifold, and connect up all instruments and auxiliary gear.

For instructions regarding the mounting and testing of the airscrew and the first trial flight.

If new piston rings, new pistons, new connecting rod bearings, etc, have been installed, the engine should be run in on the ground for about half an hour, gradually increasing the speed to 1,000 rpm. At intervals of 5 to 10 minutes stop the engine for an examination. Preliminary fights should also be made with the engine on low throttle. Only after the engine has been run in by 5 to 10 hours’ flying (according to the importance of the new parts) may the engine be again run at full speed without danger.

[pic]

[pic]

[pic]

FITS

Storage of the Crankshaft

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |- 0.027 |- 0.005 | |Play must remain |

|B in Diameter |0.02 |- 0.02 | |Play must remain |

|C in Diameter |- 0.004 |- 0.032 | |Play must remain |

|D in Diameter |0.01 |- 0.035 | |Play must remain |

|E in Diameter |0.06 |0.045 |0.12 |Play must remain |

| | | |höchst zulässig | |

[pic]

Main and nebenpleuelstangen

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.095 |0.069 |0.15 | |

| | | |höchst zulässig | |

|B in Overall |0.2 |0.1 |0.2 | |

|Length | | |höchst zulässig | |

|C in Diameter |0.065 |0.05 |0.1 | |

| | | |höchst zulässig | |

|D in Diameter |- 0.03 |0.0 |0.01 | |

| | | |höchst zulässig | |

|E in Diameter |- 0.03 |0.0 |0.01 | |

| | | |höchst zulässig | |

Main connecting rod may be nachearbetet only by the manufacturer.

[pic]

Piston with Rings

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Overall |0.092 |0.048 |0.15 | |

|Length | | |höchst zulässig | |

|B in Overall |0.0925 |0.0475 |0.15 | |

|Length | | |höchst zulässig | |

|C in Diameter |0.06 |0.045 |0.1 | |

| | | |höchst zulässig | |

|D in Diameter |- 0.005 |- 0.015 |0.02 | |

| | | |höchst zulässig | |

[pic]

Cylinder and Piston

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.530 |0.470 |0.8 | |

| | | |höchst zulässig | |

|Cylinders rebore, if drilling large as 108, 15 pistons auswechsein, if diameters smaller than 107,35 |To out-drive only from the |

| |manufacturer |

| |mass of the cylinder drilling |Upper Measure |

| |mm |mm |

|Normal Cylinder |108.0 |0.0 |

|K2 Cylinder |108.2 |0.2 |

|K4 Cylinder |108.4 |0.4 |

|K6 Cylinder |108.6 |0.6 |

The rebored cylinders are drawn at the flange with K2, K4 and K6

[pic]

Valve with Fuhrung

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.150 |0.105 |0.4 | |

| | | |höchst zulässig | |

[pic]

Valve Lever With Socket

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.073 |0.018 |0.12 | |

| | | |höchst zulässig | |

|B in Diameter |0.045 |0.015 |0.08 | |

| | | |höchst zulässig | |

Pins fur valve levers renew, if Durchmeser is (2) 11.94

[pic]

Cam Drum

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.08 |0.022 |0.11 | |

| | | |höchst zulässig | |

|B in Total Width |0.18 |0.14 |0.25 | |

| | | |höchst zulässig | |

|C Entirely in the |0.4 |0.3 |0.5 | |

|Pitch Circle | | |permissible | |

[pic]

Storage of the Intermediate Impulse Wave to the Cam Drum

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in the |0.08 |0.022 |0.11 | |

|Durchmeser | | |höchst zulässig | |

|resounding | | | | |

|he needle wave | | | | |

|B in total caustic |0.18 |0.15 |0.3 | |

|Solution between | | |höchst zulässig | |

|the approach | | | | |

|disks | | | | |

[pic]

Tappet with Guidance

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.03 |0.02 |0.08 | |

| | | |höchst zulässig | |

|B in Overall |0.053 |0.018 |0.1 | |

|Length | | | | |

|C in Diameter |0.03 |0.015 |0.043 | |

|D in Total Width |0.215 |0.1 |0.25 | |

|E in Diameter |0.005 |- 0.02 | + 0.015 | |

| | |firmly |höchst zulässig | |

|F in Diameter |0.06 |0.03 |0.12 | |

| | | |höchst zulässig | |

|G in Total Width |0.04 |0.02 |0.1 | |

[pic]

Storage of the Magnet Drive Shaft

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.0 |- 0.016 | |Play must remain |

|B in Diameter |0.0 |- 0.016 | |Play must remain |

|C in Diameter |0.037 | 0.0 | |Play must remain |

|D in Diameter |0.002 |- 0.02 | |Play must remain |

[pic]

Storage of the Lateral Ripple

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.06 |0.038 |0.1 | |

| | | |höchst zulässig | |

|B in Diameter |0.06 |0.038 |0.1 | |

| | | |höchst zulässig | |

|C in Total Width |0.02 |0.1 |0.4 | |

| | | |höchst zulässig | |

|D in Width |Ca. 1 mm | | |

[pic]

Fuel Pump Drive

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.06 |0.035 |0.10 | |

| | | |höchst zulässig | |

|B in Total Width |0.15 |0.1 |0.4 | |

| | | |höchst zulässig | |

[pic]

Oil Pump

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.04 |0.018 |0.08 | |

| | | |höchst zulässig | |

|B in Diameter |0.02 |0.01 |0.06 | |

| | | |höchst zulässig | |

|C in Diameter |0.02 |0.01 |0.06 | |

| | | |höchst zulässig | |

|D in Total Width |0.015 |0.01 |0.06 | |

| | | |höchst zulässig | |

|E in Total Width |0.015 |0.01 |0.06 | |

| | | |höchst zulässig | |

| | | | | |

|F |1.1 |0.9 | | |

[pic]

Druckluft-Verteiler ?

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.06 |0.035 |0.10 | |

| | | |höchst zulässig | |

|B in Total Width |0.015 |0.1 |0.04 | |

| | | |höchst zulässig | |

[pic]

Tachometer-Antrieb ?

|Play |Large width |Smallest |Hochstzulassiges |Remarks |

| |Unit play |Play |Spiel bei | |

| | | |Oberholung | |

|A in Diameter |0.05 |0.03 |0.088 | |

| | | |höchst zulässig | |

|B in Total Width |0.015 |0.10 |0.3 | |

| | | |höchst zulässig | |

[pic]

Schnit by the aerobatics carburettor

-----------------------

x) This precaution may be dispensed with if the tank is of special construction and has a space provided for the recirculated oil.

x ) Only for engines without snap coupling, up to engine No. 21880.

[1] Explanation of footnotes : Tools are numbered according to our Tool Kit List F1 141. For illustrations see this List. (1) Lw1. (2) For Siemens bolted hubs: Lw 2 with Lw 4 and Lw 3; for Rupp or metal-airscrew hubs see F1 141.

-----------------------

Tighten up to stop

Hole for tommy, diam 10

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