Classic cars forum & vehicle restoration.

NONORT · Joined: 26 Apr 2012 Posts: 55 Location: Southampton

Hi there, Does anyone know what oil should be in the starter switch on a Rolls 20hp. The car that I am working on had the switch bypassed many years ago. I would like to get the original switch working as the Austin lorry foot switch is not very Rolls like. And on the far side of the car when in the driving seat. not very elegant when setting off to have to shuffle across the seat to press the pedal? Also any front seat passenger is likely to press it by accident, this has happend in the past. According to the owner.

NONORT · Joined: 26 Apr 2012 Posts: 55 Location: Southampton

Have filled the switch with engine oil apparently it doesnt realy matter what you use. It is supposed to stop the arc between the contacts as these are covered by the oil. Thus elliminating the air required for the spark to take place

Kelsham · Posted: Mon May 28, 2012 7:43 am Post subject:

I must admit I was baffled by your original question. Is the idea to prolong switch contact life?

I have never heard of switches damped by oil.

Regards Kels.

NONORT · Joined: 26 Apr 2012 Posts: 55 Location: Southampton

I suspect that it is typical over engineering that Rolls seemed to have adopted to increase realiablity. The exhaust silencer is joined to the main pipe by 24 2BA nuts and bolts the number of chesse head screws that hold the water jacket covers in place are phenonminal. They must have got something right though as many old Rolls cars are still around. Dont think we will be able to say that of many Fiat 500's in eighty years time. I must have a go at adding some pictures to my posts as a picture tells a thousand words etc etc. The next project on the car will be to re invigorate the Magneto ignition system, which is there to back up the new fangled coil ignition system. All for now.

Julian · Joined: 19 Apr 2010 Posts: 278 Location: Warrington

NONORT · Joined: 26 Apr 2012 Posts: 55 Location: Southampton

The Rolls runs on SAE 20 which may be thinner than some hydraulic oils. But many thanks for pointing me in the right direction. How about the oil used in arc welders? I think the idea behind the 20 grade oil is to make sure that it is the quantity of oil going through the bearing not its pressure that is important any ideas? The Morris Bullnose that I am involved with has an oil pressure of 3lbs when hot. This according to the manual is 'good'.

Julian · Joined: 19 Apr 2010 Posts: 278 Location: Warrington

Peter_L · Posted: Mon May 28, 2012 5:03 pm Post subject:

In my early days as an electrician within the UK Coal Industry, working on oil filled switchgear, handling high voltage and current, was commonplace.

Perhaps your local power supply company or electrical contractors who work on industrial equipment may be able to help out. However, oil filled switchgear is likely less common that it was 40+ years ago.

Using oil to prevent arcing would have allowed the switch to be built a little smaller than airbreak version and increase the working life.

NONORT · Joined: 26 Apr 2012 Posts: 55 Location: Southampton

I will have to try and get a cross sectional picture of the switch. Its operation is more of a submerged switch rather than a solenoid or toggle action switch. It is operated by a foot pedal next to the clutch pedal. This action is converted across the car by levers and rods to the top of the switch. An arm takes this motion and presses down the plunger arrangment in the switch housing. The housing is approximatley 2" dia and 4" long. The switch originaly failed due to the weakest link in the whole system being the little rocking lever that does the plunger pressing. It only had a cross section 3/32" X1/8". So you can see a size ten boot on the foot pedal would put a huge strain on it. It seems to be working well now. When I get a chance I may drain the engine oil in the switch and replace it with ATF.
Many thanks guys for all the help after a slow start I think we can call this problem 'fixed'. All the best.