By Josh Cosford, Contributing Editor
Where you mount your power unit’s hydraulic pump plays a role in performance, reliability, price and real estate. Some configurations are effective for performance but challenging to maintain, while others ensure reliability while taking up acres of floor space. This guide will help you decide what method to mount your hydraulic pump on your power unit.
In tank vertical mount
This method submerges the pump below the oil level, discouraging cavitation from excess suction while orienting the motor vertically to save space. The reservoir lid must be removable to allow the technical to sandwich the pump, motor and bellhousing against the cutout.
In tank hydraulic pump mount design
Performance/Reliability: Flooded suction ensures good inlet conditions. Low oil may cause aeration or catastrophic dry running.
Maintenance: Removing the pump is time consuming and often messy. Tubes or hoses attached to the top of the power unit must be removed, and the entire lid, pump and motor must be hoisted to access the oily pump below.
Floor Space: Highly compact.
Cost: Economical
Tank top horizontal mount
This configuration uses a horizontal style bellhousing combing the pump motor in a horizontal orientation mounted atop the reservoir. This combination is mounted using the feet of the motor, while the pump is entirely supported by the bellhousing.
Tank top mounted hydraulic pump design
Performance/Reliability: Most likely to cavitate since the pump must pull fluid from below, creating a vacuum. Suction tube/pipe size is critical.
Maintenance: Very easy since the pump is not flooded with oil, and the elevated height makes for ergonomic and easy access.
Floor Space: Slightly larger than the vertical mount, but still only as large as the reservoir.
Cost: Economical.
L-shaped side mount
One of the favorite designs of engineers, this configuration has a large drip tray platform extended from the side of the reservoir, and plumbing runs horizontally to the pump inlet.
Performance/Reliability: Excellent, as the inlet line mounted low in the reservoir offers flooded suction, ensuring constant flow even when the oil level drops to a dangerous level.
Maintenance: Can be complicated and messy, as the pump is mounted low on the drip tray, and technicians better pray a ball valve was installed on the suction line, or else the reservoir must be drained prior to maintenance.
Floor Space: Perhaps the biggest downside to the L-Shaped reservoir is the massive footprint.
Cost: Can run fairly high, especially if appropriate safety measures are heeded, such as locking and monitored ball valves for the suction line.
Elevated reservoir
These units elevate the reservoir on a frame with the pump mounted directly below, providing the flooded suction advantage with reduced floor space compared to the L-shaped.
Performance/Reliability: The ultimate in flooded suction with positive pressure from the elevated design.
Maintenance: The most difficult part is due to the flooded suction, cramped space under the reservoir, lowered pump/motor location, and possible interference from plumbing and components.
Floor Space: Fairly compact — typically the same floor space as the tank top horizontal mount.
Cost: Expensive due to the frame, extra safety components and extensive labor.
Filed Under: Components Oil Coolers, Engineering Basics, Pumps & Motors
