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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).
Confirming a telegram and discussing modifications to a servo braking system, comparing it with Hispano and 40/50 HP models.

Identifier  ExFiles\Box 106\1\  scan0089
Date  15th May 1926
  
To Hs{Lord Ernest Hives - Chair}; from R.{Sir Henry Royce}
c. to CJ. BJ. BY.{R.W. Bailey - Chief Engineer}

X5410

RH{R. Hollingworth}/M15.5.26.

'INDIA' X.5770 X.5370
X.5310 X.5410 X.5420

We give below a confirmation of telegram sent
you yesterday :-

"TRY 3 SPLINES ONLY IF STILL WORKS OUT INCREASE
"TO 120º STILL USING ONLY 3 UNDERSTAND LARGER FIRST
"SPEED PINION DOES NOT WORK OUT IF THEREFORE 120º
"UNSATISFACTORY USE THIS IF SERVO DRIVE FOUND TO
"BE WELL LUBRICATED FIT HOLLOW WORM WHEEL INCREASE
"LENGTH OF WORM AND MADE SERVO DO LESS WORK BY
"INCREASING ANGLE OF CAM OR DIA ALSO GOOD TO
"REDUCE FRONT BRAKING BECAUSE OF EFFECT ON STEERING
"ROYCE".

With reference to your report on India naturally, I
was sorry to hear so many faults and wired you accordingly.
You will see that there are 4 points to be proved on the servo
or modified if they are needed. You will see my idea that with
the 20 HP. car the servo need only do about half the braking,
and there being light weight on the front wheels it is advisable
that the proportion of front braking should be less.

I have no doubt that if the servo drive is designed
and made correctly that it will be sufficiently large for the
purpose because the car is not as heavy and fast as the Hispano.

The proportions of braking can be less by the servo
than by the foot than in our 40/50 HP. practice because the
main is as big and the car is not so fast and heavy, so let us
reduce the front wheel braking by reducing the duty of the servo.

Comparing the servo drive with the Hispano, it will
be noticed that we run our servo considerably faster, and use
a bigger angle of action. This reduces the load on the servo
drive. My impressions are that we are better off for contd:-
  
  


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