They are designed to serve equipment and machinery that need strong pressurized actions to power their functions or parts of their functions. These are functions that could not be supported by the lesser power produced by electric motors.
Hydraulic motors, for example, help raise the wing flaps of airplanes and power the lifting of industrial cranes. Some other of the many, many machines with which hydraulic motors are used include: agitator and mixer drives, crane drives and self-driven cranes, conveyor and feeder drives, drilling rigs, cars and trucks, drum drives for digesters, high-powered lawn trimmers, the wheel motors of military vehicles, shredders, trench cutters, trommels, kilns, excavators, marine winch drives, and plastic injection machines.
Hydraulic motors are constructed with a fair amount of simplicity. Its three main parts are the pump, reservoir, and cylinder. Of course, a hydraulic motor would be nothing without the addition of pressurized fluid, usually a type of oil, which creates motion by pushing against it so that the motor’s rotating components spin all the more quickly and generate mechanical energy.
To work, a small pneumatic engine pumps oil from the reservoir, where it goes from an inlet valve to an outlet valve and through a series of gears and cylinders or turning vanes, depending on the motor’s design. Because hydraulic motors are driven by engines, they are also called hydraulic drive motors.
There are a few different types of hydraulic motors, namely, vane, gear, and piston motors. They are each named for the rotating component they use.
Vane motors function using a rotor contained inside a housing with an eccentric bore, that has vanes that slide in and out of it. The sliding motion of the rotor vanes is created by a force differential brought on by an unbalanced force of pressurized fluid.
Gear motors consist of a driver gear and an idler gear. To generate power, high pressure oil is forced into one side of the gears, where it flows around outskirts of the gears to the outlet port, where the gears then interlock and disallow the oil from flowing back out. Here, the gears rotate, generating energy.
Piston motors may use an axial piston pump or a radial piston pump. An axial piston pump consists of an odd number of pistons, arranged in a circle around a cylinder block, to regulate pressure and flow. A radial piston pump, on the other hand, use pistons mounted around an eccentrically-balanced center shaft, which either radiate inward or outward.
In addition to the basic motor types, there are a few different types of specialized motors, modified for semi-specific applications. These include hydraulic wheel motors, high speed hydraulic motors, and high torque hydraulic motors.
Hydraulic wheel motors are built directly into wheel hubs, where they contribute the power the wheels require to rotate. Depending on the size of the machine and the power of the motor, a hydraulic wheel motor can control just one or multiple wheels.
High speed hydraulic motors provide higher than normal amounts of power by converting hydraulic pressure into force with an elevated number of rotations per minute.
High torque hydraulic motors, on the other hand, achieve increased torque by running at low speeds, which is why they are often called low speed-high torque (LSHT) motors.
Also, if the occasion calls for it, hydraulic motors with strokes as small as less than one inch can be put in place of motors that take up more space.
In order to build the best hydraulic motor possible, manufacturers must take a number of factors into consideration, including the state of the relief valves, fluid reservoir, and pump, which must be endowed with levels of strength, capacity, and power that match the needs of the fluid that will go through them. This fluid, in turn, must be chemically stable and compatible with the metals with which the motor is made, and it must be a good lubricant. The material of the interior components and main enclosure must be chosen as well. For the best results, manufacturers should select a durable metal, like steel or iron, that can weather both high operating speeds and pressure.