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).
The wear characteristics and endurance testing of contact breaker points for a pump.
| Identifier | ExFiles\Box 163\1\ img040 | |
| Date | 21th January 1938 | |
| -2- The tension on the contact blade and depth of the points will affect the setting, assisting to break the points slightly earlier in the stroke if the blade is stiff and the points new, but a weak spring and worn down points will never reduce it below the initial setting of 4 holes. The wear on the points with this type will have to total .062" before the points do not make contact but the thickness of Tungsten is approximately .025" on each point and in practice the bulb of the wear takes place in the negative points. Also with this type of contact the load on the points is limited by the strength of the contact spring and it does not have to take the inertia load of the outer arm or load of the toggle spring. We have noticed in endurance tests that the contact covers contain a good deal of powdered Tungsten and hope a reduced loading may improve this. We have completed 600 hours endurance with a similar type of gear to the S.U. without trouble of any kind and the point wear seems small. This pump is also fitted with a positive guide to the spindle to prevent side thrust in the toggles with its attendant wear on the points and mechanism. In view of the above facts we intend to concentrate on a thorough test of the S.U. standard contact breaker and run endurance on both the H.P. and ordinary pump. The objection originally raised because of the contact noise is not serious and can quite easily be silenced if we find it objectionable. Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems} | ||