Hydraulic pumps and hydraulic motors are two unlike machines that work on hydropower. The following is a quick brief on the main distinctions between these two machines:
Pump: A pump is generally, a container with regulated flow rate used to shift fluid from one place to another. It might be powered by an engine or motor which uses energy created by the fluid flow to do mechanical work. The commonest industry used types of pumps are centrifugal pumps that apply rotating drum for creation of highly pressured streams; they are efficient in moving a lot of liquid at faster speeds.
Motor: A motor is a device for converting mechanical power into action/ movement. This can be caused by some external source like electrically operated motors or it may occur naturally because of objects in motion as found in gears. Using motors varies from day-to-day applications such as cars, boats and tools among others. Majority of pumping engines however are internal combustion engines; Diesel or gasoline fuels them.
The hydraulic pump creates flow while the hydraulic motor converts fluid power into mechanical power
A hydraulic pump enables a greater amount of pressure than is within the tank, allowing it to run at a higher pressure level than that produced by the system itself. In this case, hydraulic energy can be found besides what is normally provided through weights like vessels and lorries.
Hydraulic motors, however, make use of vibrating pistons to convert electrical power into mechanical force. The shafts are connected with pistons which are driven by electric power from an alternator or battery. To provide motion for such motor, the piston moves back and forth inside cylinders filled with fluid. Consequently whenever such movement happens, fluid in cylinders takes different forms as well as temperature to act therefore as source of heat energy during operations since it changes its shape.
The hydraulic pump generates pressure while the hydraulic motor uses pressure to create torque
Today, the hydraulic motor is one of the most widespread electric motors in industry’s application because it can deliver high torque and speed at low levels of expense and power usage.
Unlike other sources like gearboxes or flywheels, an electric motor maintains a constant speed of rotation without any feedback from outside. This makes it suitable for applications like pumps and motors where regulation of the velocity is not necessary.
Electrical power may be supplied either directly through a rectified supply or indirectly via an inverter which converts AC current into DC current suitable for driving motors (see below). For cases where there are no variations in frequency between output voltage, instead of direct DC supplies, AC-DC converters are often used.
The hydraulic pump is powered by an electric motor while the hydraulic motor is powered by fluid pressure
A generator, linked through an electric motor and a fluid pressure in the system, is one of them. Electricity produced by the generator while spinning is saved in batteries or capacitors for use later. These sources are tapped into when there is a need for more power in the system.
The pressurized fluid from the hydraulic system goes to an oil pump that draws oil from an oil reservoir and sends it through several conduits and valves to other parts of the machine which are usually other components.
The hydraulic pump typically has a higher power density than the hydraulic motor
Pumps and fans are some of the small-scale applications where one can typically find hydraulic motors. Water supply systems, sewage treatment plants, for instance, use hydraulic pumps for example. A single large pump is used in a domestic wastewater plant to push all the waste throughout the plant.
Their power density distinguishes these two types of motors from each other. The amount of energy required per unit volume or mass (wattage) is called power density. For instance, if you have an electric motor with 1 horsepower that produces 1HP per second and has a weight of 100 pounds, then the power density would be 10 horsepower/second/pound (10 hp/s/lb). If you have an electric motor with 3 horsepower which delivers 1HP/s in a tank weighing 100 pounds then its power density will be equal to thirty hp/ s/lb (30 hp/s/lb).
By and large, hydraulic motors can deliver much more or less powerful outputs at lower pressures as compared to electric ones when they are operating at higher pressures. However, due to their smaller size than electric motors, most of these hydraulic motors tend to be inefficient on overall basis.
The efficiency of the hydraulic pump is typically lower than the efficiency of the hydraulic motor
The losses are involved in this system, for instance the power consumption and friction. Its size and type are what determine the efficiency of a pump. In comparison to a large pump with similar internal volume, smaller pumps have high efficiencies.
Typically, efficiency of hydraulic motor is higher than that of a hydraulic pump. This is because all energy is used up in moving fluid through a pipe or cylinder; there are no losses in the system. The amount of energy lost depends on how quickly you want to move something or how much force you want to exert on it.
The speed of the hydraulic pump is typically fixed while the speed of the hydraulic motor can be varied
In this case, the pump can be operated at some speed, while the motor can also drive other things at much higher velocities than that.
This happens because pumps are made to move fluid at a steady rate whereas motors are designed for high power inputs and turning quickly. The pump may draw more fluid than is required to move it further but once there it won’t stop until empty of fluids.
Additionally, this implies that most motors are engineered to perform better under higher speeds than what they are typically used in. In such a case, if you have a motor denoted as 10,000 RPMs (revolutions per minutes) which you want to increase its speed up to 20,000 RPMs (1/2), then no problem since they still work together effectively since they have an equal load.
The size of the hydraulic pump is typically smaller than the size of the hydraulic motor
Compared to a hydraulic pump, a hydraulic motor is generally bigger because it possesses additional energy and must run at faster velocities. If your’ pump is small, for instance, with only few horse powers; then a big motor would be necessary to cope up with the demand.
A hydraulic pump will always be smaller than the hydraulic motor because its power level is low and it runs at low speeds. For instance, if you have a small pump of few horsepower, then you will need to buy a large motor in order to meet the demand.
The hydraulic pump typically has a lower operating temperature than the hydraulic motor
The reason being that the hydraulic motor is an AC motor while the hydraulic pump is a DC motor. The operating temperature of a DC motor depends on how much current it draws to operate and how much power it draws to run at full speed. The operating temperature of a low powered DC machine is lower than that of a high powered one.
An AC machine’s operating temperature goes with frequency and voltage. Specifically, at low frequencies (20 Hz or less), due to its small size, its operating temperature is very low, making it can be cooled quite easily by means of fan system. As a matter of fact, most contemporary AC motors have fans already installed in them so as to cool them down even more. However, if we increase their frequency or voltage above rated specifications, then they start getting hot since their electrical resistance increases with higher frequencies and voltages. This causes them to draw even more power from the source which further increases their heat output such that they become hotter than they would if operated at lower frequencies and voltages!
The hydraulic pump typically has a shorter life span than the hydraulic motor
1.The hydraulic motor is heavier than the hydraulic pump and as such it therefore requires more power to start.
2.If the fluid pressure in a hydraulic motor is not higher than that in a hydraulic pump, then it will malfunction.
3.The rotor seal of the hydraulic motor cannot be replaced like that of some pumps, so regular maintenance is required for this kind.
4.These motors also lack access ports and seals around worn pistons such as those found on other types of pumps making repairing them difficult.
The cost of the hydraulic pump is typically higher than the cost of the hydraulic motor
Most pumps are usually designed in a way that they can be used with different types of motors. There has to be a properly sized coupling in place and also certain amount of pressure exerted on them; hence, they may not be light compared to other types of pumps.
On the flip side, it is generally possible for hydraulic motors to be made lighter than many other kinds of motors, and also more compact in size. Further still, they do not need any separate cooling system because they come as hardwired heat sinks. As such, either motor type can serve where there is insufficient room for larger pump or else when we need pulling power at low speeds which bigger pump cannot achieve.
The internal leakage of the same type of hydraulic motor is larger than that of the hydraulic pump
A hydraulic pump has a smaller internal leakage compared to that of the same type of hydraulic motor because an electric motor has a high internal leakage which must be reduced. However, in minimizing leakage from electric motors, we should remember that these motors are meant to work under high speed conditions and produce high power, hence their internal leakage will be very large.
The reason for this is that hydraulic pumps do not have pistons on the other hand hydraulic motors perform their work with a piston pump. Moreover; hydraulic pumps use oil as a medium rather than air or water as transmission medium to achieve high-speed transmission and low power consumption.
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