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).
Clearance volume tests conducted on the LeC. 2961 petrol pump.
| Identifier | ExFiles\Box 17\5\ Scan138 | |
| Date | 13th August 1932 | |
| R.{Sir Henry Royce} From HS{Lord Ernest Hives - Chair}/Sl. c. to SS.{S. Smith} c. to Por. c. to W. c. to Sy. c. to Da.{Bernard Day - Chassis Design} HS{Lord Ernest Hives - Chair}/Sl.2/WA.{Mr Wallis}13.8.32. LeC. 2961 PETROL PUMP. CLEARANCE VOLUME TESTS. A test previously taken to ascertain the clearance, and swept volumes of the LeC. 2961 type head, showed that the former was 9 cc's and the latter 11 cc's. In order to reduce the clearance volume, a special - solid - diaphragm washer was made to screw on to the plunger above the fabrics, replacing the standard dished washer and nut, also the screwed end of the plunger was reduced to the level of the solid washer. The piston stops in the head were also removed to allow the piston to reach its maximum position. With the pump assembled, and the fabrics held at the top of the stroke by the normal pressure of the spring, the head was filled with a low temperature melting point metal. Before retesting the capacity, a wax impression was taken of the shape of the head. In extracting this, the metal representing the fabric waves stuck to the wax - being delicate. If that metal had remained in position the clearance volume would have been still further reduced by a considerable amount. The clearance volume when rechecked measured 4 cc's, i.e. a decrease of over 55%. Slow speed dry pumping tests were taken with the reduced clearance head, and comparative tests taken with a 9 cc clearance volume head. | ||