# Pressure and torque relationship

### How to Convert Torque to Force | Sciencing The equation, Force = Torque ÷ [Length × sin (Angle)], converts torque into The head of the wrench grabs a bolt and applies pressure to it. Hello, I have a problem converting torque to pressure. need, but I've always been curious about the torque - clamping force relationship. Can someone clarify the calculated pressure from using a torque There is a general equation that estimates the axial loading applied by the.

Horsepower relative to weight on the other hand is more relevant to the maximum speed of a vehicle. See our article on power for more detail on this. It is important to recognize that while maximum torque and horsepower are useful general specifications, they are of limited use when making calculations involving the overall motion of a vehicle. This is because in practice both vary as a function of rotational speed. The general relationship can be non-linear and differs for different types of motor as shown in Figure 4. In internal combustion engines the combustion pressure and temperature increase with rotational speed.

An optimum combination of these variables occurs at a specific rotational speed, leading to the observed peak in available torque.

Mechanical Power: Torque and Speed

Relationship of available torque to rotational speed for different sources. How can we increase or decrease torque? It is often necessary to increase or decrease the torque produced by a motor to suit different applications. Recall that the length of a lever can increase or decrease the force on an object at the expense of the distance through which the lever must be pushed. For example, we have heard engine builders, camshaft consultants, and other "technical experts" ask customers: In fact, the opposite is true, and you should be clear on these facts: Figure 1 Referring to Figure 1, assume that the handle is attached to the crank-arm so that it is parallel to the supported shaft and is located at a radius of 12" from the center of the shaft.

In this example, consider the shaft to be fixed to the wall.

### Torque and Pressure

Let the arrow represent a lb. Because the shaft is fixed to the wall, the shaft does not turn, but there is a torque of pound-feet pounds times 1 foot applied to the shaft. In the same way that one ton is a large amount of weight by definition, poundsone horsepower is a large amount of power.

The definition of one horsepower is 33, foot-pounds per minute. Consider the following change to the handle-and-crank-arm sketch above.

• Basics of Force, Torque and Pressure

The handle is still 12" from the center of the shaft, but now, instead of being fixed to the wall, the shaft now goes through the wall, supported by frictionless bearings, and is attached to a generator behind the wall. Suppose, as illustrated in Figure 2, that a constant force of lbs. In other words, the "arrow" rotates with the handle and remains in the same position relative to the crank and handle, as shown in the sequence below.

That is called a "tangential force". Figure 2 If that constant lb. The output shaft of the gearbox of the engine in Example 4 above turns at RPM. The point to be taken from those numbers is that a given amount of horsepower can be made from an infinite number of combinations of torque and RPM. Think of it another way: In fact, in cars of equal weight, the smaller engine will probably race BETTER because it's much lighter, therefore puts less weight on the front end.

AND, in reality, the car with the lighter 2-liter engine will likely weigh less than the big V8-powered car, so will be a better race car for several reasons. Measuring Power A dynamometer determines the POWER an engine produces by applying a load to the engine output shaft by means of a water brake, a generator, an eddy-current absorber, or any other controllable device capable of absorbing power. Then it applies various factors air temperature, barometric pressure, relative humidity in order to correct the observed power to the value it would have been if it had been measured at standard atmospheric conditions, called corrected power.

Power to Drive a Pump In the course of working with lots of different engine projects, we often hear the suggestion that engine power can be increased by the use of a "better" oil pump. Implicit in that suggestion is the belief that a "better" oil pump has higher pumping efficiency, and can, therefore, deliver the required flow at the required pressure while consuming less power from the crankshaft to do so.

While that is technically true, the magnitude of the improvement number is surprisingly small.

## - Power and Torque -

How much power does it take to drive a pump delivering a known flow at a known pressure? We have already shown that power is work per unit time, and we will stick with good old American units for the time being foot-pounds per minute and inch-pounds per minute. Since flow is more freqently given in gallons per minute, and since it is well known that there are cubic inches in a gallon, then: Since, as explained above, 1 HP is 33, foot-pounds of work per minute, multiplying that number by 12 produces the number of inch-pounds of work per minute in one HPDividingby gives the units-conversion factor of Therefore, the simple equation is: When the equation is modified to include pump efficiency, it becomes: So suppose your all-aluminum V8 engine requires 10 GPM at 50 psi.

The oil pump will have been sized to maintain some preferred level of oil pressure at idle when the engine and oil are hot, so the pump will have far more capacity than is required to maintain the 10 GPM at 50 psi at operating speed.