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).
Analysis of a Bijur lubrication system, discussing issues like entrapped air, leaks, and oil viscosity.
| Identifier | ExFiles\Box 27\1\ Scan116 | |
| Date | 8th March 1929 guessed | |
| - 3 - After a drip plug is disconnected about 2 cc of oil runs out. When the joint is replaced the pump plunger goes down about 1" rather fast on the first shot. This is while the slug of air is being forced out of the drip plug which has been disconnected. Subsequent shots are slow and even. This immediate discharge of any entrapped air through the first available drip plug is one of Bijur's big claims in which by virtue of using stationary metering apparatus he has an immense advantage over Bowen and others. It depends entirely on using fine bore pipes throughout the system. Some cars seem to go through life with a tendency to fall rather fast during the first inch or so of every shot. This of course is due to some leak or rather two leaks at different levels in the system. Sometimes the owner notices this and gets into the habit of giving two shots. As we have improved our workmanship these cases have grown fewer. Personally I would search for the leaks until the pump fell evenly at each shot, but actually it does not seem to matter to the lubrication of the car. That is we have never found a case of a part not getting oil through this cause. (4) Air in oil. We have had no trouble with air in the oil itself. The design of the tank guards against this by having an inlet valve which will not close until the oil is "solid" below the plunger. That is if the oil level has run low in the tank, the pump simply refuses to work, the plunger falls right back as a warning to the driver, and no air is pumped into the line. (5) As explained above we have no objection to air getting into the system when disconnecting a drip plug from the line. We find that about 1 or 2 cc leaks out, and the consequent air bubble escapes at the first pull of the pump. (6) Oil. We have made some viscosity tests and an arbitrary "zero flow" test, as explained below:- We should say that Bijur No. 1 and Bijur "Moderately Heavy" are definitely not suitable for real zero conditions and unheated garages in the U.S. -continued- | ||