Technical Info - Worn Hub Diameters

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With time the threads of the lock nut and the hub wear and eventually become unsafe.

This abrasion is accelerated if the wheel is not fitted tightly.

The table below details wear criteria for Rudge-Whitworth wheels from Type 5 introduced in 1908 through to Types 42 to 120 introduced in 1912.

The earlier types were used with wooden spoked wheels.

Type	Test for worn Lock Nut Dia. (inches)	Test for worn Hub Thread Dia. (inches)	Re-fitted Lock Nut Dia (inches)	Re-chased Hub Thread Dia (inches)	Min Hub Dia (inches)	Max Dia inside Wheel Hub (inches)
	A	B	C	D	E	F
5	3.69	3.77	3.751-3.756	3.74-3.75
6	2.815	2.895	2.876-2.881	2.865-2.875
8	1.825	1.905	1.886-1.891	1.875-1.885	3.225	3.175
9	2.815	2.895	2.876-2.881	2.865-2.875	4.626	4.576
42	2.211	2.291	2.296-2.301	2.292-2.295	2.424	2.374
52	2.627	2.707	2.702-2.707	2.698-2.701	2.84	2.79
62	3.011	3.091	3.076-3.081	3.072-3.075	3.224	3.174
72	3.377	3.457	3.442-3.447	3.438-3.441	3.59	3.54
80	3.760	3.84	3.825-3.83	3.821-3.824	3.973	3.923
90	4.141	4.221	4.206-4.211	4.202-4.205	4.354	4.304
100	4.587	4.667	4.652-4.657	4.648-4.651	4.8	4.75
120	5.16	5.24	5.225-5.23	5.221-5.224	5.373	5.323

If the lock nut is worn enough to admit a plug of the diameter in column A, it should be replaced.

If the hub thread is worn enough to enter a ring of the diameter given in column B, the hub should be chased down to the diameter given in column D, and fitted with a specially made lock nut to the diameter given in column C.

If the hub serrations are worn smaller than the diameter in column E, the hub should be replaced.

If the wheel serrations are worn to a larger diameter than the diameter in column F, the wheel centre should be replaced.