Rolls-Royce P II fuel gauge

[Machinist60]

Hello I am new to this forum.  I am helping a 1930 RR P II owner with Restoration.  Picture here

https://www.coachbuild.com/forum/viewtopic.php?f=49&t=655&start=40

Park Ward Phantom II Sports Saloon, 1930, #117GN. 

The gas (petrol) gauge is of the manometer type similar to the Hobson K-S petrol telegage.

http://www.hells-confetti.com/Images/Instruments/Telegauge/Hobson Telegage instructions.pdf

While one tube is sufficient to supply the pressure at the bottom of the tank to the manometer in the dash, Rolls-Royce has three tubes running from the pressure sensor in the fuel tank to the dash indicator.

I would like to understand the function of the two extra tubes.  One tube is simply sealed at it's end at the bottom of the pressure sensor at the bottom of the fuel tank.

If anyone has information or links it would be appreciated.

Thanks, John.

Edited August 27, 2019 by Machinist60
Clarity (see edit history)

[DavidAU]

https://rroc.org.au/wiki/images/5/57/20_25_Owners_Handbook_Part_9.pdf

Edited August 27, 2019 by DavidAU (see edit history)

[Machinist60]

Many thanks DavidAU.   Google did find that link for me but I dismissed it because the first page described an electric fuel gauge, I did not look further.  I now understand the purpose of the the two extra tubes.  Hopefully we will be able to get the gauge working, it appears we may be only missing the small hand pump.  There are a lot of Rolls parts in the shop, a good search may turn it up.

An Enots oiler showed up and we have worked through all the dripper plugs of the Bijir chassis lubrication system (an amazing pump, the one in this car puts out 80 psi at the start of the stroke)

Currently working on roof covering, carpeting, upholstery and head cloth in the Packardward body.