4.3 Hydraulic Head And Rotor


Use this assembly procedure if the hydraulic head and rotor only have been removed from the pump.

4.3.1 Rotor plug

Remove the distributor rotor (4) from the hydraulic head and mount it in the special tool (1), in a vice.

If the rotor plug screw (2) is loose, remove it, clean and degrease it and carefully smear the threads with "Araldite" AV100 resin mixed with hardener HV100 in the recommended proportions. Use the absolute minimum of resin necessary to ensure satisfactory locking of the threads.

Refit the plug to the rotor, using a new seal washer.

Use the special hexagon key (3) to tighten the plug screw to the specified torque.

Refit the rotor to the hydraulic head, ensuring that no oil reaches the plug, and leave the assembly to one side for the recommended resin curing period.

4.3.2 Preparation of the hydraulic head

Screw the transfer pump rotor (1) into the distributor rotor and leave it finger-tight.

Place the hydraulic head on the bench with the transfer pump rotor facing downwards. Fit a new Oring (6). Fit the rear scroll plate (4) into its groove in the end of the head, matching the direction of the arrow with the direction of pump rotation as marked on the identification plate. Align the slot (2) in the scroll plate with the cutout (5). Remove the plunger retaining clip (3) from the rotor.

Early hydraulic heads were fitted with an Oring of 2.0mm cross-section; later heads require an O-ring of 3.0mm cross-section.

4.3.3 Fitting the hydraulic head to the pump housing

Lightly lubricate the inside of the pump housing with clean test oil. Mount the housing onto the Hydraclamp assembly plate with the governor surface uppermost. Align the hydraulic head drive tang with the drive shaft slot and carefully insert the hydraulic head into the housing. Push the head in until the O-ring abuts the housing.

4.3.4 Final location of the hydraulic head

Grip the hydraulic head and, using a twisting action, push the head firmly in so as to fully engage the head into the housing.

Ensure that the scroll plate slots (1) are in line with the metering valve bore and that the three head fixing points (2), (3) and (4) in the housing are now fully aligned with their respective holes in the head.

If the head will not move axially and is not jammed in the housing, the rotor drive tang has probably become disengaged. Slowly twist the drive shaft and the distributor rotor relative to each other to re-align the drive tang and the slot in the drive shaft. Check that the transfer pump rotor is flush with the outer face of the hydraulic head.

4.3.5 Checking drive shaft end-float.

Carry out the procedure for checking the drive shaft end-float as described in section 4.2.10.

Have more questions? Submit a request