Rolls-Royce Archives
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From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Issues and solutions for speedometer drives, clocks, and trafficators.

Identifier  ExFiles\Box 168a\4\  img201
Date  22th April 1941
  
Rm{William Robotham - Chief Engineer}/RC.{R. Childs}8/ST.22.4.41 - 7 -

impregnating with Ellison's insulation varnish and cement type SR.65, or by some other varnish which is unaffected by heat. In any case, we feel the design is not good, since the outside case should be metal in place of the existing bakelite.

The adoption of the Lucas coil will also save the cost of the ballast, about 2/6.

SPEEDOMETER DRIVE.

Flickering of the Speedometer pointer was proved to be due to excessive torsional flexibility in the cable, and we have now gone back to the large diameter drives. This move has cured the trouble.

The dimensions of the respective cables are as follows:-

TYPE. CASE. CABLE.

ATF 14 Unpolished galvanised 0.163" diam.
steel 0.344" diam.

Larger Brass finished 0.237" diam.
Type 0.438" diam.


CLOCKS.

We have recently issued a report on the behaviour of electric clocks, and Rs.{Sir Henry Royce's Secretary} has been in touch with Mr. Nichols, who has promised a more efficient unit.

We have come across a new trouble with these clocks, in that the hand setting stem unscrews and falls out. We have had two cases, one on 1-MT-1, after only three days running. These may have been loose at the start. Special attention is now being given to all clocks in order to find the trouble.

TRAFFICATORS.

An old trouble, in which the trafficator will not fall to its "off" position after being used if the car reaches a speed of 50 M.P.H. before the switch cancels the operation, has been cured by the fitting of a narrow vane on the outside edge of the arm (Rm{William Robotham - Chief Engineer}/RC.{R. Childs}3/ST.4.J.41).
  
  


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