Hydraulic drive is the best way to drive a diaphragm pump as there are generally too many issues with using PTO-driven shafts, particularly for the safety of the operator.

Diaphragm pumps (540 RPM models) that are hydraulically driven need to be set up so they cannot be run below a minimum of 450 RPM or above a maximum of 540 RPM. Operators should install a fitting on the hydraulic drive block so that the pump cannot be run over 540 RPM no matter what the hydraulic setting or oil pressure is. 

Centrifugal pumps may not be able to perform as intended if the hydraulic plumbing is not correctly set up or adjusted. Hydraulic motors on hydraulic centrifugal spray pumps need to be matched to the hydraulic capacity and system of the tractor.

Always check the pump manufacturer’s website for the most appropriate model of hydraulic motor to match the tractor model or hydraulic oil flow capacity of the sprayer.

When establishing the hydraulic plumbing to and from the hydraulic motor on the spray pump, it is very important to have a ¾” hydraulic hose going back to the dedicated ‘motor return RET’ fitting on the tractor, not the ‘case drain TANK’. 

Plumbing the hydraulics correctly can reduce the back pressure, which needs to be no greater than about 50 psi. This will help to reduce heat build-up and will extend the life of the seals in the hydraulic motor.

While it is not common practice, some centrifugal pumps can be operated at pressures of up to 10.0 or 12.0 bar, provided the hydraulic plumbing is correctly selected and installed.

Tip

When connecting the hydraulics always connect the return hose first and the pressure hose last and do the opposite when disconnecting the hydraulics: remove the pressure hose first and the return hose last.