You want to balance the overall system efficiency with the desired performance when developing your hydraulic system. You must first adjust the motor to your particular system performance before adjusting the pump. Which motor you choose will alter the overall system’s architecture.
An actuator that produces rotating actuation when properly coupled to a hydraulic system is called a hydraulic motor. Whether the motor is unidirectional or bidirectional depends on how the system is designed. A pump uses a rotating actuation to transfer hydraulic fluid out of the unit, whereas a motor takes flow into itself and emits a rotary actuation. This is the only difference between the two types of motors and pumps. This post will offer a guide on what hydraulic pumps and motor to select.
Consider the Load
The choice of the motor comes first because, according to application design best practices, you should start with the load needed and work your way back to the prime mover, which is the pump that will supply the fluid power to the motor so that it can operate as you need or expect.
Sorts of Motors
Every motor type has a certain set of uses which is the superior option. A small gear motor that is intended to run at a maximum of 3,000 psi and 2,000 rpm, for instance, will be operating under excessive stress, which will shorten its lifespan even though it is technically within its ratings if it is used in an application where it must run continuously at 3,000 psi and 1,0000 rpm. A motor with a higher rating that will last longer in this application would be the wiser choice. Yes, a better-rated motor will cost more, but its lifespan and performance may make up for this.
What Factors to Consider?
- Closed or open loop: For 75% of industrial hydraulic applications, open-loop systems are used. Hydraulic circuits use open return lines. Multi-axis applications and upgrades are possible with open-loop systems. Closed-loop systems, prevalent on mobile machinery and winches/cranes, connect return lines to the pump inlet. This eliminates control valves for accurate, compact control. Closed-loop steering systems operate best with rotary actuators but can use cylinders.
- Flow rate: Determine the application flow rate, then account for component wear and leakage that affects efficiency. Pump flow is specified.
- Pressure: Pumps create flow, not pressure. It flows strong enough to overcome pump outlet load pressure. Cylinder outlets create enough pressure to lift the load, but tank outlets generate little. Different pumps have different maximum pressures. Radial piston pumps have 700 bar, and vane pumps 100 bar.
- Power: Flow times pressure equals hydraulic power. Calculate hydraulic power. Do not guess the power of a similar pump that may be overspecified. Various pressure pump performance charts exhibit power-flow rate relationships.
- Speed: Speeds vary for hydraulic pumps. The bent-axis piston pump can only run at 3000 RPM, whereas the external gear pump can achieve 4000. Ensure the pump’s speed and flow rate meet the application because running it at a lower speed affects efficiency. Speed impacts electric or internal combustion propulsion unit efficiency.
- Maintenance: Pump purchase is only part of its ownership cost. Maintenance prevents performance loss, early failure, unscheduled downtime, and high TCO. Correct pump maintenance replaces worn parts before additional damage. Some pumps are more expensive to maintain. Consider usability, accessibility, system longevity, and maintenance ease.
Conclusion
Keep in mind that choosing the right hydraulic motor begins with the application’s intended performance and then moves on to the prime mover, or pump. The cost of your motor alternatives must then be compared to the level of sophistication you desire for the entire system.
