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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).
Bump test performed on the latest pattern Firth springs for 40/50 Front Springs.

Identifier  ExFiles\Box 119\2\  scan0216
Date  29th October 1929
  
COPY
BUMP TEST.
RE 40/50 FRONT SPRINGS
Test of Latest Pattern Firth Springs, (F71980/1), 1100LBS & 1150 LBS.
CONDITIONS: 2" CAMS SET AT 180°. DRUMS MAKE 105 R.P.M. TYRES AT 65LBS/[]'.
LOAD ON FRONT OF CHASSIS = 1000LBS.

SPRING DETAILS.
FRACTURE    POSITION OF LEAF    POSITION OF FRACTURE FROM CENTRE BOLT    APPROXIMATE RUNNING TIME    THICKNESS OF LEAF    BRINELL AT FRACTURE

N°012. NEAR SIDE. F71980. 1100 LBS.
FLEXION: COMPRESSION = 1·5"; REBOUND = 2·8".
POSITION OF FRACTURES.
A    BOTTOM.    2" TO REAR.    16 - 23.    .200"    363
B    NEXT TO BOTTOM.    2" TO REAR.    18 - 23.    .204"    363
C    TOP.    2·5" TO REAR.    22 - 33.    .298"    401

N°013. OFF SIDE. F71981. 1150 LBS.
FLEXION: COMPRESSION = 1·8"; REBOUND = 2·5".
POSITION OF FRACTURES.
D    TOP.    2" TO REAR.    13 - 46    .303"    375

N°014. OFF SIDE. F71981. 1150 LBS.
FLEXION: COMPRESSION = 1·7"; REBOUND = 2·5".
POSITION OF FRACTURES.
E    5TH (FROM TOP)    1·5" TO REAR.    46 - 10    .236"    415
F    6TH " "    1·5" TO REAR.    46 - 10    .228"    401
G    7TH " "    1·25" TO REAR.    46 - 10    .217"    388
H    8TH " "    1" TO REAR.    46 - 10    .223"    388
J    BOTTOM    1·5" TO REAR.    46 - 10    .210"    401
M    TOP    16·5" TO FRONT.    35 - 2    .284"    388
  
  


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