Integrating a new hydraulic pump—whether a gear, piston or axial-piston model—into a vehicle-mounted hydraulic system or a maintenance operation is a critical stage. A pump is a precision mechanism with internal clearances measured in microns. The first few minutes after the post-installation start command are among the most decisive moments in the pump’s total field service life. Dry running, reverse rotation or a blocked line during this initial movement can cause irreversible internal wear and mechanical damage. To prevent these risks, the critical checks specified in HMLIFT pump catalogue standards should be carried out in the correct sequence.

Critical Checks That Secure the Initial Start-Up

1. Fluid-Fill Verification (Preventing Dry Running)

Pumps must rotate with a continuous supply of fluid so that their moving elements—gears, pistons and distribution plates—remain lubricated. The pump housing and suction line must be confirmed as completely filled with oil. After the tank is filled, observing the settling period recommended in the catalogue notes allows air trapped in the system to escape.

2. Position Check of Valves in the Lines

The shut-off valves at the tank outlet, including the T valve, and all circulation paths must be checked to ensure that they are fully open. A valve accidentally left closed can starve the pump of oil within seconds and damage its internal mechanism through intense frictional heat.

3. Matching the PTO Direction of Rotation

The direction of rotation of the power take-off (PTO) must match the pump’s designed direction exactly—clockwise (CW) or counterclockwise (CCW). Reverse rotation prevents the pump from establishing correct suction and pressure and may stop the system from operating or damage the pump. On bi-rotational HMLIFT models, the inlet and outlet fittings must also be checked against the installation diagram to confirm that they are connected to the correct ports.

4. Axial Alignment Check of the Flange and Shaft

The pump’s mechanical integration with the PTO flange or cardan-shaft connection must be inspected. Bolts must be tightened to the specified torque, and there must be no axial misalignment. Alignment errors impose radial loads on the shaft and rapidly shorten bearing and seal life.

5. Inspection of Hose Lines and Protective Caps

The fitting connections on the pressure and suction hoses must be reviewed. One of the most common installation errors is connecting hoses without first removing the factory-fitted plastic protective caps from the ports of new components. This can block the flow path completely and damage the system.

6. Verifying Viscosity for Seasonal Conditions

The viscosity grade of the hydraulic oil must be confirmed as suitable for the operating environment—for example ISO 32 in winter, ISO 46 in summer and ISO 86 at high temperatures. Oil that is too thick makes suction difficult in cold conditions, while oil that is too thin may prevent the initial lubricating film from forming correctly.

7. Low-Speed, Unpressurised Start-Up Principle

Initial start-up must never be performed at high engine speed or under load. With the minimum intermittent speed limit of 300 rpm taken into account, the system should be started with the engine at idle and the directional control valve in neutral, allowing open circulation. The pump should then run without pressure for several minutes so that the internal oil film can stabilise.

8. Monitoring the Oil Warning Hole

An important safety detail in HMLIFT pump designs is the oil warning hole in the housing. During initial start-up and subsequent field checks, this opening should be monitored for any leakage. Fluid emerging from the hole provides the technician with an early indication of the condition of the shaft seals.

Conclusion

A few minutes of technical care during commissioning, combined with compliance with catalogue procedures, creates a sound foundation for the new pump and the hydraulic system to operate efficiently and reliably for many years.