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 the performance of Maybach dogs on the 14-EX chassis, detailing issues with gear engagement.
| Identifier | ExFiles\Box 182\M19\ img124 | |
| Date | 26th February 1931 | |
| To R.{Sir Henry Royce} To Da{Bernard Day - Chassis Design}/Hdy.{William Hardy} From Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} c. to Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} EY. ORIGINAL Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey}3/KT.26.2.31. MAYBACH DOGS (ON 14-EX). X2200. The first tests on the Maybach dogs on 14-EX were not very successful owing to - (1) The springs not being sufficiently strong allowing the dogs to come out of mesh on the overrun. (2) The bolts shearing in the 3rd. and 4th. speed engaging dogs. In this first condition it was possible to engage two gears at once owing to the weaker springs. Stronger springs were fitted and larger bolts to replace those which had failed; the car was in this condition when it was sent to West WitteringHenry Royce's home town last week. Our impressions of it are as follows. (1) Changing from 3rd. gear to top, by preselecting the gear (by moving change speed lever) and releasing accelerator pedal when the change is required. (a) Bad clicking from dogs during the period before the speeds of the dogs synchronise; the intensity of the clicking being governed by (1), spring strength tending to push the dogs into engagement (2), lapse of time before speeds of dogs synchronise (3), Face angle on dog clutches, the greater the angle the more pronounced is the clicking. (b) No bad transmission jerk is obtained by changing as above as long as the engine speed is not less than the third motion shaft speed before engagements are attempted. At very low speeds engagement tends to become jerky (i.e. gets to the stage where engagement occurs when driven dog speed slightly exceeds speed of driving dog). (2) Engaging top gear, car stationary. Very difficult owing to face angle of the dogs being excessive; however slowly the first motion shaft is allowed to rotate (by manipulation of the clutch) the top gear dog will not drop into engagement before the point A.{Mr Adams} on the driving gear has overshot the point A.{Mr Adams} on the driven gear. [Diagram with text: '1ST MOTION SHAFT DOG', 'A', 'TOP GEAR DOG (STATIONARY)'] (3) Engaging 3rd. Gear, car stationary. Extremely violent | ||