How to Find Your Machine's Auxiliary GPM & PSI

You need the hydraulic specifications at the attachment circuit—not just the machine's engine horsepower or total pump capacity. The two key numbers for matching a hydraulic drive are auxiliary flow in GPM and maximum auxiliary pressure in PSI.

1. Check the Operator or Service Manual

Look for the auxiliary attachment circuit specifications. Useful terms include auxiliary hydraulic flow, standard flow, high flow, maximum auxiliary pressure, relief pressure and attachment circuit.

Do not use total implement-pump flow unless the manufacturer specifically identifies it as available to the attachment circuit.

2. Check the Machine Display / Auxiliary Settings

Many newer excavators, skid steers and compact track loaders allow the operator to select or limit auxiliary flow. The maximum machine specification and the currently programmed attachment setting may be different.

3. Standard Flow vs High Flow

Some skid steers and compact track loaders are offered with optional high-flow hydraulics. Two machines with the same model name can therefore have different attachment capability.

Verify whether your specific machine has the high-flow option rather than assuming from model size alone.

4. Ask the Dealer Using the Serial Number

If the machine was offered with multiple hydraulic packages, the dealer can often identify the installed configuration from the machine serial number.

5. Verify Pressure, Not Just Flow

High GPM does not automatically mean high torque. For a given drive, pressure determines torque potential while flow primarily controls rotational speed. A machine can have plenty of flow but insufficient pressure for the required drive torque.

6. If the Specifications Are Still Uncertain

A qualified hydraulic technician can test the auxiliary circuit with appropriate flow and pressure test equipment. Testing should be performed using the correct procedure for the machine and attachment circuit; do not improvise a dead-head pressure test.

Other Hydraulic Details That May Matter

• One-way or two-way auxiliary flow
• Return-flow restrictions
• Case-drain requirement
• Coupler size and type
• Relief-valve setting
• Whether flow can be electronically limited
• Continuous-flow capability

What to Send Rev-Pile

• Machine make and model
• Serial number if hydraulic configuration is uncertain
• Auxiliary flow in GPM
• Maximum auxiliary pressure in PSI
• Standard-flow or high-flow option
• Application: screw piles, earth drilling, rock drilling or trenching
• Required torque or desired hole diameter if known

Read: Hydraulic Flow, Pressure, Torque & RPM   |   Get an Equipment Recommendation