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).
Description of the procedure for balancing a V8 crankshaft using various machines.
| Identifier | ExFiles\Box 126\3\ scan0078 | |
| Date | 16th February 1937 guessed | |
| - 2 - also the amount is shown by a vernier scale. From an attached chart the out of balance moment is converted into holes as drilled in the balance weights and states the number and the depth. Whatever the number of holes, 3 being the maximum on each balance weights, these are drilled proportionately about the line which is marked where weight has to come off. The above being a general description of the machine, the procedure is as follows. Clamps representing the big end reciprocating weights are put on the crank pins, the crank is then dropped into place on the roughing balance machine (10 ozs) and the out of balance is recorded by chalking on the balance weights the number and depth of holes, together with the centre line of where the drilling is to be carried out. The crank is then lifted off the balancer to the drilling machine which is no more than 3 ft. away and drilled according to the chalking on the inner large balance weights, this drilling machine only using 1 size of drill diameter. From this drilling, the crank is passed on to the next balancer which also is only 3 ft. away and is more sensitive to balance having a capacity of unbalance of (4 ozs). Similar to the first machine, the out of balance is recorded by chalking on the outer small balance weights and is handed over to another drilling machine which has a smaller diameter drill than the first. Finally the crank is placed on an inspection balancer which has limits reading on a clock face representing 1/4 oz inch and only within this limit are they passed. The flywheel and clutch are balanced as a separate unit. The whole operation of balancing the V8 crankshaft takes 12 minutes, but other than the actual machines it is their relative layout that is so efficient, i.e., rough balance to large driller, sensitive balance to small driller and finally to the inspection balance. With regard to floor space occupied by these five machines this would be no more than approx. 20' x 9'. In order that weight be taken off the balance weights more or less centrally, these are credited with extra weight in the casting such that the cranks as received for balance are 8 ozs heavy on the balance weight side. The crankshaft has a normal heat treatment and a final Brinell of 350 approx. throughout the section as compared with our 640 on the surface down to a core of 350. | ||