Both motors as well as pumps are used in hydraulic systems to control flow and pressure of the fluid so that it can perform some work mechanically. Hydraulic motors using pistons and piston pumps use a piston-cylinder arrangement to push fluids. Despite their similar appearance and similar way of operation, there exist several fundamental differences that make them more appropriate for their respective applications.
Design Considerations:
Flow Direction: Motors and pumps are optimized for fluid flow in one direction only. Switching these roles may not yield efficient fluid handling.
Seals and Bearings: The seals and bearings in hydraulic motors, designed generally for being driven by hydraulic oil with certain conditions may not be best suited for pumping applications where much higher pressures could be encountered.
Efficiency: The design of the motor and pump is based on efficiency towards their primary functions. Motor used as pump will result in reduced efficiency and high energy consumption.
Internal Leakage: Over long time hydraulic motors have shown themselves to be less effective when operating as pumps due largely to greater internal leakage tolerance which characterizes them generally.
Short-Term vs. Long-Term:
While it’s technically possible to use a piston-type hydraulic motor as a hydraulic pump for a short while or during emergencies, doing so over an extended period is ill-advised for several reasons:
Wear and Tear: Continuous use of motor as pump may lead to faster wear-and-tear thereby affecting its life span/reliability.
Performance Decline: Over time, you might notice performance decline such as decreased efficiency and flow rates that could impact overall hydraulics system integrity.
Warranty and Maintenance: Continuingly using a hydraulic motor as a pump can void any warranty that existed before; it would also necessitate increased frequency of checks with parts requiring replacement thus increasing running costs.
Summary:
The principle of operation between piston-type hydraulic motors besides piston pumps is quite similar although these units are optimized depending on their particular functions. The following sections explain why using a hydraulic motor as a pump over an extended duration is generally not recommended due to design considerations, lower efficiency, potential accelerated wear and tear plus other operational concerns that may arise. For long-term applications, it’s advisable to use devices specifically designed for the purpose you intend.
