D12              PTO / Pump Fitment              

Please check that your order is complete and that no damage in transit has occurred. Please inform your supplier immediately of any shortages or damage.

Hydraulic equipment can cause death, personal injury and property damage.

The equipment should be fitted and commissioned by a suitably qualified person.


  1. Any specific instructions for the particular PTO are supplied. If you do not have these, please contact us. In addition to good fitting practice the following points are drawn to your attention.

  2. Check sufficient backlash between PTO gear and gearbox gear on side mounted PTOs. Insufficient backlash will typically cause whining and rapid wear resulting in both damage to PTO and gearbox.

  3. Backlash should be set to the instructions specific to the type of PTO being fitted, and should be to the manufacturer’s instructions. As a further guide, no unit should ever be run with zero backlash or a backlash so great as to cause rattling, normally evident if the backlash is greater than around 0.40mm. Backlash is expressed as a measurement of the radial movement of the PTO gear measured at the outer end of the gear teeth.

  1. Do not use more than 3 soft gaskets to achieve clearance. If more clearance is required insert metal shim gasket.

  1. Fixing studs should be secured using “loctite” or similar locking compound.

  1. Function including engage / disengage should be checked before the pump is fitted.

  1. On a rear mounted PTO take extra care to ensure that any quillshaft supplied is correct for length, engagement into gearbox spline or drive gear, and engagement into oil pump if fitted.

  2. The air supply to the PTO should normally be at the full vehicle system pressure (?-?) taken from manufacturers recommended supply points. This is especially important on clutch type PTO’s as any unsuitably low pressure will cause major damage to the clutch pack. Always check the manufacturer’s minimum and maximum pressure instructions. Air must not contain contaminates such as oil or water.


  1. Check pump rotation

  2. Before fitting the pump, lightly grease the pump shaft up to the pump seal.

  3. On applications where water or other contaminates may enter the PTO/Pump joint, fit a gasket

  4. Always bleed the pump before use, either by means of the bleed plug if provided, or by allowing oil to exit the pressure port before coupling outlet pipe.

  5. Certain pump types may require pre-filling with oil – check additional instructions.

  6. If a pump is replacing a failed unit take into account residual contamination and take steps such as oil and filter changing.

  7. Do not start the PTO / Pump under load.

  8. Check that relief valves have not been adjusted to compensate for a previously worn pump.

  9. If in doubt, always back off the relief valve before running the pump

  10. Always pressure check, by means of a suitable gauge, the system pressure before the equipment is put into service.


Hydraulic Fluids

Although not highly aggressive, hydraulic fluids may contain compounds dangerous to eyes and mucous membrane. Emergency procedures should be followed if fluid contamination occurs to eyes or internally. Medical assistance must be immediately sought in these instances. Prolonged exposure of outer skin may lead to skin complaints and should be avoided. Used oil may contain carcinogens.

Pressure Hazards

Vehicle hydraulic systems may run up to pressures of 500 bar. Fluid at this level of pressure can penetrate skin if near high pressure leaks or component failure. Penetration of contaminates in to the sub skin layer can be fatal. Fluid injection accidents are extremely serious and immediate emergency medical assistance must be sought. Suitable protective equipment must be worn when working on live hydraulic systems.

Heat Hazards

Faulty hydraulic systems can heat fluid which, being under pressure, can attain temperatures far in excess of its atmospheric boiling point and contact with components at these temperatures can cause burns. Contact with the fluid at these temperatures will cause scalding burn injuries. Immediate medical attention must be sought.

Mechanical Hazards

Hydraulic systems can store energy in the form of pressure (e.g. in hoses or accumulators) or potentially by the imposition of force due to the relative position of components and the effect of gravity or other energy storage mechanism on these components. Therefore, before any work is undertaken on hydraulic equipment, these forces must be eliminated by neutralizing the equipment.

Equipment can be neutralised by:

  1. Bleeding off under control any residual pressure.

  2. By blocking or otherwise supporting components.

  3. By returning equipment to at rest or neutral positions.

    Equipment such as tipping bodies, loader crane booms, tail lifts and excavator booms present obvious hazards in this category.