Maximizing Towing Capacity - …



Bobby Gagnon Science Project #5 June, 2013 Term 4What is torque?Torque and Low-End PowerMost drivers know that torque translates into low-end power, or the ability to accelerate the vehicle at low rpm levels. Torque moves the vehicle from a stop and helps it get up steep hills. As such, more torque is required to start a heavier vehicle than a lighter one. That's why torque is useful when towing -- torque is what allows you to pull heavy loads. When you see car ads on TV, they often discuss horsepower figures for performance and sports cars, while you're more likely to hear about torque in truck commercials.A vehicle's towing capacity refers to the amount of weight it can pull behind it. Modern trucks like 3500’s can tow up to 16,000 pounds (7,257.5 kg) - more than twice the truck's weight, which is about 7,000 pounds (3,175.1 kg). That towing capacity is related to the truck engine's torque. Your vehicle's engine creates torque and uses it to turn the crankshaft, which is connected to the transmission. The transmission gears convert this torque so that the vehicle can move and tow cargo safely.If you tow often, you know to keep your vehicle in a lower gear than normal. For a five- or six-speed transmission, that means towing in fourth; on a four-speed, third gear usually does the trick. This is because there is more torque available in lower gears, which is why it's harder to accelerate from a stop or pass another car on the highway in the highest gear, no matter how much horsepower you have.3360420742950Imagine towing a trailer up a steep hill. If you're in a truck like the F450, you've got a lot of weight behind you, so obviously you'll want to go slowly up the incline. As such, you'll be keeping your engine rpm low. Again, that's where torque comes in. Having lots of horsepower just won't help you when you need to tow an object at low rpm. For that, you need that low-end power that torque provides.Maximizing Towing CapacityMost large commercial trucks and some heavy-duty trucks have diesel engines. Diesel engines generate more torque. Since a diesel engine doesn't have spark plugs and uses compressed air to ignite fuel, the piston (cylinder) has to travel a longer distance to compress enough air for ignition. This cylinder travel distance is called stroke, and more stroke means more torque.The differences between two truck engines. A Dodge Ram truck with a 6.7-liter Cummins Turbo Diesel engine has 350 horsepower and 650 pounds-feet of torque. And another truck with a 5.7-liter gasoline V8 engine has 383 horsepower and 400 pounds-feet of torque. Answer: While the gasoline engine has a little more power, the diesel's torque completely blows it away.While the two trucks have very similar towing capacities --15,650 pounds (7098.7 kg) for the gasoline engine and 16,350 pounds (7416.2 kg) for the diesel -- all that low-end power means the diesel engine will have an easier time towing things. With a diesel engine, you won't have to rev up to start towing because the power already exists. Because you're using more energy-laden diesel fuel, diesel engines get better mileage than gasoline ones, so you'll also be able to tow longer without stopping. At the same time, a truck with a gasoline engine is going to have a cheaper base price. Diesel engines almost always cost more than gas ones because they are built to withstand greater forces from a more potent fuel. A vehicle’s towing capacity depends on many of its components, including wheels, tires, suspension and transmission. mostly, the bigger the towing job, the larger displacement engine you will need. Towing puts a lot of stress on the engine, so more torque will reduce wear and tear on the vehicle.Torque, a force that turns or tends to turn an object. The word torque comes from the Latin torquere, meaning to twist. When an object is not free to move—or when the torque is not of sufficient magnitude to rotate it—torque produces torsion, a twisting stress, in the object. The force used to swing open a door is an example of torque. Belts turned by electric motors exert torque on fans and other rotating devices. The shaft that drives an airplane propeller produces torque on the propeller.Torque = F x L, where F is the force and L is the length of the lever arm.Putting Gears to WorkGears are generally used for one of four different reasons:To reverse the direction of rotationTo increase or decrease the speed of rotationTo move rotational motion to a different axisTo keep the rotation of two axes synchronizedMost gears that you see in real life have teeth. The teeth have three advantages:They prevent slippage between the gears. Therefore, axles connected by gears are always synchronized exactly with one another.They make it possible to determine exact gear ratios. You just count the number of teeth in the two gears and divide. So if one gear has 60 teeth and another has 20, the gear ratio when these two gears are connected together is 3:1.They make it so that slight imperfections in the actual diameter and circumference of two gears don't matter. The gear ratio is controlled by the number of teeth even if the diameters are a bit off. An ExampleImagine the following situation: You have two red gears that you want to keep synchronized, but they are some distance apart. You can place a big gear between them if you want them to have the same direction of rotation:Or you can use two equal-sized gears if you want them to have opposite directions of rotation:However, in both of these cases the extra gears are likely to be heavy and you need to create axles for them. In these cases, the common solution is to use either a chain or a toothed belt.Why is torque important in off-roading?You've probably heard the term "torque" used to describe the power of SUVs and trucks. Like horsepower, it's a force that's vital to the movement and performance of all vehicles -- but especially to the four-wheel drive vehicles used in off-roading.Torque is a force that creates rotation. For example, when you're tightening the lug nuts on your wheels, you're providing torque when you rotate the nuts with a wrench. Similarly, your vehicle's engine applies torque to the axles so that your wheels will rotate. Horsepower, on the other hand, is energy that pushes a vehicle in the same direction as the applied force.Both horsepower and torque influence acceleration. Horsepower affects acceleration at high speeds, whereas torque aids acceleration from a stopping point. Because of this, torque is known as low-end power. Since off-road driving isn't performed at the high speeds of highway driving, low-end power is crucial in pushing your vehicle through the many slow-downs and speed-ups you encounter at ditches, debris-ridden paths, bumpy terrain, and muddy or snowy roads.Torque is measured in pound-inches or pound-feet, which means the applied force (pounds) is multiplied by distance from the center (inches or feet). So, for example, if the wrench you're using to tighten your lug nuts is two feet long and you apply 100 pounds of pressure to turn it, you're creating 200 pound-feet of torque. A vehicle with a lot of torque has a significant amount of applied force to help propel it.Torque force is distributed to your wheels by a transfer case (also known as a gearbox). The transfer case sits behind your vehicle's transmission and distributes torque to the axles through the drive shaft. Most transfer cases have a gear reduction, known as 4-Low, that can send more torque to your wheels. When it comes to your off-road vehicle, this increased torque will come in handy when you're navigating rough, hilly or uncertain terrain. ................
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