A pump is the source of fluid flow in many hydraulic and process systems. The manifold does not generate hydraulic energy on its own; instead, it receives pump flow and distributes that fluid through valves and internal passages according to the needs of the machine.
Pump selection and manifold design are closely related because the manifold must carry the flow delivered by the pump without creating unnecessary restriction or unstable operating conditions.
Pump Function
Flow, Pressure and Hydraulic Pumps
Hydraulic pumps move fluid from a reservoir into the pressure side of a hydraulic circuit.
Industrial hydraulic pumps are used in systems where pressurized fluid powers cylinders, motors, clamps, lifts, tooling, presses, and other equipment.
The pump produces flow. Pressure develops when resistance in the system opposes that flow. A heavily loaded actuator therefore requires more pressure than the same actuator moving with little external resistance.
Pump Technologies
Pump Types Used With Manifold Systems
Different pump technologies are suited to different fluids, pressure ranges, flow requirements, and control strategies.
Hydraulic circuits typically use positive-displacement pumps because a predictable amount of fluid is moved during each rotation or pumping cycle.
A hydraulic piston pump uses reciprocating pistons to move hydraulic fluid and can be incorporated into systems with demanding pressure and control requirements.
Other fluid-handling applications may instead use equipment such as centrifugal pumps, depending on the medium and process requirements.
Manifold Connection
Routing Pump Flow Into a Manifold
The pump outlet can connect to a manifold supply port through pipe, tubing, hose, fittings, or a closely integrated mounting arrangement.
Once inside the manifold, the supply passage may feed directional valves, pressure-control valves, check valves, proportional controls, relief functions, and actuator branches.
Supply passage dimensions should correspond with the maximum flow expected from the pump during machine operation.
Return Circuit
Returning Hydraulic Fluid to the Reservoir
Hydraulic fluid leaving an actuator commonly returns through manifold passages and valves before traveling back toward the reservoir.
Return passages can experience significant flow, particularly when large cylinders retract or when several functions operate at the same time.
Excessive restriction on the return side can create backpressure and contribute to heat generation or reduced actuator performance.
System Sizing
Matching Pump Flow to Manifold Capacity
A pump capable of high flow requires valves, passages, filters, fittings, and hoses that can carry that flow without creating excessive pressure loss.
Pump Inlet Conditions
Cavitation and Restricted Pump Supply
A pump needs an adequate supply of fluid at its inlet. Restrictions in suction lines, filters, fittings, or reservoir connections can reduce the fluid available to the pump.
Poor inlet conditions can contribute to noise, unstable operation, reduced output, component damage, and other symptoms associated with cavitation.
The manifold is normally located downstream of the pump, but overall system design should still account for both pump inlet and outlet conditions.
Filtration
Protecting Pumps and Manifold Components
Contamination can damage pumps and travel into manifold valves, actuator seals, motors, and precision control components.
Filters can be incorporated at selected locations within the hydraulic circuit to control contamination while maintaining acceptable pressure drop.
Explore Manifold Filtration →Diagnostics
Pump Problems That Can Appear to Be Manifold Problems
Slow actuators, low pressure, noisy operation, heat, inconsistent motion, or inadequate motor torque can sometimes originate with the pump rather than the manifold.
Diagnosis should compare pump outlet conditions with pressure and flow farther downstream. If adequate flow leaves the pump but is lost across a manifold valve or passage, the restriction is elsewhere in the circuit.