4.2 Drive Shaft Assembly, Governor Weight Cage, Pump Housing, Head And Rotor


4.2.1 Drive shaft assembly

A) Roller shoe spacers and timing disc

Insert the spacers (1) into the recesses in the drive shaft (2). In the case of two-plunger pumps, place the short spacer in the position noted during dismantling. Secure each spacer with the appropriate Torx screw (3) and washer.

If an internal timing disc is specified, fit the disc (4) prior to inserting the spacer screws. Ensure that the marks made on the disc and the drive shaft during dismantling are in line. If the disc (or the shaft) is to be replaced, transfer the mark(s) to the new component.

B) Tightening the torx screws

Secure the rotor end of the drive shaft in a softjawed vice and, using the appropriate Torx adaptor (1), tighten each screw progressively to the specified torque value.

It is essential that the drive shaft is clamped across the slots as shown and that only the minimum necessary clamping force is imposed upon the shaft, to avoid distortion.

C) Roller shoe plate and roller catch plate

Carefully mount the drive shaft (1) in a vice fitted with soft jaws and with a "Tommy bar" through the cross-hole to resist the screw tightening torque as shown. Fit the roller shoe plate (2), followed by the roller catch plate (3), to the drive shaft. Secure the plates using the four screws (4), tightened to the specified torque value with the appropriate "Torx" adaptor (5).

4.2.2 Governor weight cage and drive shaft assembly

A) Weight cage assembly

Place the weight cage (1) on the Hydraclamp mounting plate.

Fit the fly-weights (2) into the weight cage. If less than six flyweights are specified, they must be placed into the weight cage symmetrically. The "Toes" of the flyweights should be at the bottom of the cage, facing inwards. Fit the thrust washer (3), making sure that it rests on the toes of the flyweights, and then insert the thrust sleeve (4) with its flat end against the thrust washer.

B) Assembly of the drive shaft to the weight cage

Fit the drive shaft assembly (1) through the thrust sleeve (2) and the weight cage (3).

4.2.3 Inner bearing, scroll plates, and cam ring

A) Fitting of the inner bearing

Fit the inner bearing (1) to the drive shaft assembly

with the scroll plate recess (2) uppermost.

B) Fitting the rollers and shoes to the drive shaft

Fit the roller and shoe assemblies (1), (2) and (3) to the drive shaft, ensuring that the long shoe (4) (fitted into the slot without the shoe spacer) has its lubrication slot (5) facing towards the drive end of the pump.

Two-plunger pumps have shoes of equal lenght, each with a lubrication slot (5) which must be fitted facing the drive end.

C) Fitting the scroll plate to the inner bearing

Fit a scroll plate (1) into the recess of the inner bearing, ensuring that the direction of the arrow (2) matches the direction of rotation on the pump name plate. The slot (3) in the scroll plate must be aligned with the centre of the wide access slot (4) in the drive shaft inner bearing.

D) Fitting the cam ring

Fit the cam ring (1), ensuring that the direction of the arrow (2) matches that on the name plate label.

Ensure that the cam screw hole (3) lines up with the tapered clearance slot (4) on the drive shaft inner bearing.

The slot, in turn, should be aligned with the gap between any two pockets in the weight cage. This is so that the assembly will not foul the head of the advance device stud when the pump housing is fitted over the drive shaft.

E) Fitting the rear scroll plate

Fit the rear scroll plate (1), ensuring that the direction of the arrow (2) matches that on the name plate label, and that the slot (3) aligns with the slot in the front scroll plate and the centre of the wide access slot (4) in the drive shaft inner bearings.

4.2.4 Hydraulic head rotor plug

Remove the distributor rotor from the head and mount it in the special tool (1), in a vice. If the rotor plug (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. Refit the plug to the rotor, using a new seal washer. Use the special hexagon key (3) to tighten the plug to the specified torque.

Refit the rotor to the hydraulic head, ensuring that no oil reaches the plug and leave to one side until the recommended curing time has passed.

4.2.5 Assembly of the drive shaft to the hydraulic head

A) Transfer pump rotor and outer scroll plate

Screw the transfer pump rotor into the distributor rotor and leave it finger-tight. Place the hydraulic head on the bench with the transfer pump rotor downwards.

Fit a new O-ring (1) to the head groove.

Lift the rear scroll plate off the cam ring and place it, inverted, in the recess (2) in the head; this ensures that the scroll plate is correctly installed with respect to pump rotation. Remove the plunger retaining clip (3).

B) Fitting the drive shaft to the head

Align the hydraulic head drive tang with the drive shaft slot. Lift the drive shaft assembly from the Hydraclamp; invert the assembly, ensuring that it remains pushed together, and place it on to the hydraulic head.

If necessary, rotate the drive shaft relative to the rotor to engage the rotor tang with the drive shaft slot. The metering valve bore (1), the two scroll plate slots (2) and the wide access slot (3) in the drive shaft inner bearing should all be in line.

C) Checking component alignment

On the other side of the assembly a gap in the weight cage (1) should be in alignment with the drive shaft inner bearing tapered clearance slot (2).

the hole for the cam advance screw (3) and the head locating bore (4) in the hydraulic head.

4.2.6 Housing

If the housing stud (1) has been removed, fit a new stud.

Mount the housing in the Hydraclamp and use the dome nut (3), together with a temporary 5/16 24 UNF lock-nut (2), to tighten the stud to the specified torque. The lock-nut should be no more than 5mm thick, to allow sufficient thread engagement for the dome nut.

If end float is controlled by an external shim washer which abuts the pump housing spigot, the oil seal(s) must be installed prior to fitment of the drive shaft. (see section 4.2.9).

Remove the housing from the Hydraclamp.

4.2.7 Fitting the pump housing to the drive shaft and hydraulic head

A) Fitting the housing to the internal components

Lightly lubricate the inside of the pump housing with clean test oil and carefully lower it onto the assembled drive shaft until it contacts the hydraulic head O-ring; avoid excessive downward pressure.

B) Mounting the assembly on the Hydraclamp

Position the Hydraclamp so that the mounting plate (1) is horizontal; keep the complete assembly together, invert it, place it onto the mounting plate and secure it with the three clamping screws and washers (2).

C) Alignment of the drive shaft and rotor

Position the pump horizontally. Lubricate the hydraulic head O-ring with clean test oil and, using a twisting action, push the head firmly into the housing until it is fully engaged.

If the hydraulic head will not move axially, the rotor drive tang has probably become disengaged. Slight twisting of the drive shaft and the transfer pump rotor relative to each other will re-align the drive tang and the slot in the drive shaft.

Check that the transfer pump rotor is flush with the end face of the hydraulic head.

4.2.8 Transfer pump rotor

Insert a suitable tommy-bar (1) through the governor weight cage aperture into the hole in the drive shaft to prevent the drive shaft from rotating.

Fit the transfer pump adaptor (2) to the transfer pump rotor and tighten the rotor to the specified torque value.

Temporarily fit the transfer pump blades to the rotor to check that they are free to move within their slots.

If they are tight, unscrew the rotor, check that the threads and blades are clean and undamaged. Refit and tighten the rotor. If the blades are still tight, replace the rotor.

4.2.9 Drive shaft oil seals

If end float is controlled by a shim washer fitted in the seal bore and abutting the inner face of the pump housing, the drive shaft, ball, shim and circlip must be fitted and end float checked and corrected by the use of alternative shims before the seals are fitted See also the note in section 4.2.7

A) Single oil seal

The drive shaft seal punch kit includes the seal protection cap (1). Fit the cap to the drive shaft.

Moisten a new oil seal (2) with clean test oil, ensure that the seal is the correct way round as noted during dismantling and use the punch (3) and a hide (or rubber) mallet to drive the seal fully into the recess in the pump housing. Remove the protection cap. The outer face of the oil seal should be just below that of the pump housing (4).

Fit the thrust washer (5) and circlip (6) to the drive shaft.

B) Double oil seal

Use the double oil seal punch kit to fit each seal in turn to the housing recess. Ensure that the seals face the direction noted during dismantling. When specified, fit the circlip into the pump housing groove between the seals.

C) Internal circlip

Position the shaft so that the recess (1) is uppermost. Fit the ball (2) to the recess and align the notch in the thrust washer (3) with the ball. Fit the washer with the grooves facing the pump housing. The notch should retain the ball.

Fit the circlip (4) into the groove and position the gap in the circlip either side of the ball.

Check drive shaft end float and adjust as necessary with the appropriate shims.

4.2.10 Checking end-float and radial play

End-float may be measured with or without the hydraulic head fitted to the pump housing; however, the Inner bearing must be in position before radial play is measured.

A) End float

Fit the appropriate adaptor (1) to the drive shaft thread. Screw in the dial gauge holder (4), and fit the dial gauge (3). Adjust the gauge pin to contact the machined face of the pump housing (2).

Push the drive shaft inwards and set the dial gauge to zero. Pull the drive shaft outwards and note the maximum gauge reading. End-float should be between 0.05mm and 0.2mm. If it is outside that tolerance, correct it by the use of alternative shims.

B) Radial play

If the original housing and shaft are to be used and radial play at the main bearing was found to be within the limits stated below, it should not be necessary to measure radial play at this stage. If either item has been replaced play must be measured.

With the pump and dial gauge (1) mounted rigidly relative to each other adjust the gauge pin to bear against the drive shaft (2). Push the shaft radially towards the gauge and set the gauge to zero. Pull the shaft radially to the opposite extreme and record the gauge movement.

Repeat the readings with the gauge repositioned as shown at (3) and (4). Do not rotate the drive shaft. Reject the housing if either the maximum play or the difference between the measurements exceed the figures below.

Belt drive type: Max. play = 0.22mm, Max. difference = 0.1mm

Gear or hub drive type: Max. play = 0.27mm, Max. difference = 0.2mm

4.2.11 Fitting the drive shaft key or pin

Fit a new Woodruff key (1) or (and only if necessary) fit a new key pin (2) to the drive shaft. whichever is specified. In the case of the pin, note that the hole is deeper than the pin length; the pin should be carefully driven in until its protrusion is between 0.9 and 1.00mm. (dimension "A").

If specified, fit the coupling to the drive shaft and secure it with the spring washer and nut, finger tight: the drive coupling may subsequently need to be removed for testing.

Check that the pump rotates freely.

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