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Gearboxes

When dismantling A.J.S. gearboxes, before the cover can be removed the lock nut on the end of the mainshaft must be taken off. This has a left-hand thread, and should be unscrewed by tapping with a punch in the hole provided, to the right. Behind this nut will be found either a plain steel thrust washer, located by a peg in the cover, or one washer and one ballrace.

How to take up Endplay

In both cases, excessive lateral movement or endplay of the mainshaft is controlled by fitting a thrust washer of suitable thickness until the movement of the mainshaft endways can just be felt. The plain-thrust washer type can be converted to the ballrace type by the necessary parts which can be supplied by the makers.

How to remove the High Gear

Fig. 15.-METHOD OF REMOVING TOP-SPEED GEAR.

This arrangement holds the spocket fast while the lock nut is unscrewed. To tighten up the lock nut, the chain is reversed on the sprocket.

The only difficulty that may be experienced in dismantling an A.J.S. gearbox is in removing the top-speed gear or dog. A special tool is supplied by the makers to remove or fit this part. This job can, however, be carried out in a fairly simple manner. The difficulty in removing or fitting the top-speed gear is in holding either the gear itself or the driving sprocket whilst the lock nut which holds these two parts together is unscrewed or tightened up as the case may be. The sprocket can be held rigid for the above operations by holding the gearbox firmly in a vice, by means of the lug at the bottom, then fastening one end of the front or rear chain off the machine underneath the bench, and placing the other end round the sprocket, as shown in Fig. 15. To unscrew or tighten up the lock nut, the chain has only to be reversed over the sprocket. The top-speed gear is removed from its ballrace in the gearbox by being tapped with a mallet on the screwed end. The one end of the chain mentioned above should be fastened to the bench by either a stout nail or wood screw, having a suitable size washer under its head to prevent the screw pulling through the chain link.

When Reassembling-Note

The following may be worth mentioning when gearboxes are being assembled. On the majority of A.J.S. gearboxes the sliding pinion on the mainshaft has a groove machined on one side of the teeth, in which operates an arch for sliding the pinion and engaging gear. In assembling this sliding pinion should be fitted with the groove referred to facing the gearbox cover.