Traditionally, when we talk about engines, we generally refer to internal combustion engines or electric motors. However, there are other types of motor. Among these types of motor there are physical power motors.
The so-called physical power motors are motors that take advantage of the kinetic energy or the potential energy of some element.
An example of power motors is found in hydraulic power plants. In this type of installation, the potential energy of the water is used, which when falling is converted into kinetic energy and drives a turbine. In this way, a motor, in this case a generator, performs a transformation of energy: from kinetic energy to electrical energy.
Another source of power for power engines is the use of compressed gases. In this classification we find pneumatic motors.
Physical power motors are used in multiple applications. These motors are used in some funiculars, cable cars and even in watchmaking. Some watches have a weight that drops under gravity.
Pneumatic motor
The pneumatic motor is a type of power motor that works by means of a compressed gas.
Pneumatic motors deliver movement with pneumatic energy. This can be either a rotary movement or a linear movement. When it comes to a rotary movement, it is delivered to an axis.
An example of a linear air motor is the air drill, that is, a pneumatically powered chisel used to break up a road surface when working.
The drive of a pneumatic motor is carried out with compressed air through a compressor.
Pneumatic motors offer an important advantage over electric motors in that they cannot cause sparks and are therefore suitable for work in areas at risk of explosion.
Air motors are often used in machine shops to secure bolts and nuts.
Hydraulic engine
A hydraulic motor has the function of converting hydraulic energy into mechanical work. There are a variety of hydraulic motor designs. These designs are classifiable in terms of their operation on constant and variable motors.
Hydrostatic units have a fixed relationship between volume flow and velocity, but these can be changed. They are built as hydraulic pumps (for example, as a gear pump); The energy carried by the oil flow is in turn converted into rotational energy by the action of pressure on the gears.
Axial piston motor designs are available with constant and variable stroke volumes. They are used, for example, as the driveline of excavators, in this context one often speaks of a hydrostatic transmission.
The torque generated by hydrodynamic motors is often controllable independently of speed.
The maximum torque of a hydraulic motor is determined by the pressure of the hydraulic fluid. The displacement determines the speed, it depends on the supplied volume flow.
Advantages and disadvantages of the hydraulic motor
Hydraulic motors are used in engineering much less often than electric motors, but in some cases they have significant advantages over the latter. Hydraulic motors have 3 times less volume and weigh 15 times less than electric motors of corresponding power.
The rotation speed control range of a hydraulic motor is much wider: for example, it can be from 2500 rpm to 30-40 rpm, and in some cases, for special hydraulic motors, it reaches 1-4 rpm or less.
The starting and acceleration time of the hydraulic motor is a fraction of a second, which is unattainable for high-power electric motors (several kilowatts). For the hydraulic motor, there is no danger of frequent stop and reverse. The law of motion of the motor shaft can be easily changed using the regulating means of the hydraulic drive.
However, motors have the same drawbacks inherent in hydraulic drive.
