The Mercedes Scroll-Clutch

Sir,

In reply to Mr. Anthony Bird’s query regarding the term “scroll clutch” in his letter in the November issue of MOTOR SPORT. I came in contact with one of these devices at the start of my career in I think about 1928. My employers who had an engineering business in Great Portland Street bought a World War One Mercedes Daimler German staff car.

This was an open four-seater rather on the lines of the 3-litre Bentley with a right-hand gear change outside the body.

The engine used a double-sleeve valve and the clutch consisted of two flywheels in the same shaft the inner faces of which were conical. Interspaced between the flywheels were the two cone clutches, leather lined, and between the clutches was a large tapered scroll spring which engaged the clutches when the pedal was released.

It certainly took some force to depress the clutch in this model.

The double-sleeve-valve engine was wrongly timed when bought and we had to separate the crankcase (in two halves in this car) and lever them apart in order to get the timing gears apart. We also used a bent file tang after the junkhead was removed to establish valve opening position.

I won’t go into a long description of how we tried to compress the scroll spring to assemble the clutch. Suffice to say that the car and clutch worked splendidly after assembly.

I drove it in the pouring rain from Great Portland Street to somewhere in the Vauxhall Road area across the river with four young apprentices urging me on. I had had hardly any driving experience in those days so it was quite a ride.

All the best to your splendid magazine which I have read regularly for 25 or 30 years.

Hilton. JOHN SHERRARD.