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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).
Test report on servo gear rattles, acceleration, and steering wobbles for chassis 9 G.III.

Identifier  ExFiles\Box 4\9\  09-page122
Date  30th August 1925
  
X5840

Hotel de France,
Chateauroux,
Indre. France.

GWH.{George W. Hancock - Head Chateauroux}I/Crn.30.8.25.

To: "Hs{Lord Ernest Hives - Chair}"
From: G.W.Hancock.

Chassis 9 G.III.

Continuation of tests on servo gear rattles. We have again tried the tests, as reported on the 27th inst. We have nothing further to add to the results of those tests.

Tests carried out.

Acceleration on full throttle.

The amount of amplitude of servo gear rattles is definitely increased and decreased per load applied to car. One can, by accelerating very slowly on a level road, go through the periods with almost entire absence of rattles. The rattles increase per ratio as the throttle opening is increased. The rattle is the most pronounced when car is travelling on a slight incline, and throttle is opened wide at the critical speed. The servo gear rattles also are of less amplitude when the box is cold. Also, the periods are approximately 3 to 4 miles per hour slower, viz: the period we state at 29 m.p.h. when the box is cold the maximum is 26 m.p.h. There is a difference between getting the box hot on a cool day, and on a hot day.

Amount of damping required to stop rattle.

We have not been able, and have not the appliances here, to give us the load applied to the drum on this test. By applying a load direct on to top of servo drum, as hard as one could press, the rattles could not be damped out. By using leverage and applying load on side of drum, the rattles can definitely be damped out. This was carried out by using a piece of wood, approximately 12" long, with a leverage approx. 10". This load is considerable. We can also damp out the rattles by applying the foot brake whilst accelerating. This damps the rattles as effectively as applying the load to drum by wood. These tests have been carried out on the road several times, with the same results.

Tests for steering wobbles, carried out as per your instructions.

Conditions of tests. Cross steering tube, and side steering tube ball end joints all O.K. New "Dunlop" tyres on front. Wheels perfectly balanced.
  
  


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