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RMC air suspension

Not being any where near my bus, does anyone know how the rear air suspension works on early RMs and RMCs (and RCLs)?

I know there is a separate air feed from the compressor to the rear suspension via a non return valve, but is there a second air tank? Can the bus be driven off before the rear has lifted given that air goes to the rear suspension first?

All help appreciated

My bus number (if any): RTL 960, RMC 1458, RM 1585 and several RTs

Re: RMC air suspension

We had a couple of RMCs at our depot as trainers. Drivers, engineers and conductors alike, loved them and all wanted to have a go. Everyone wanted them to go into service and would have been perfect for the 607 which was introduced too late for RMC or RCL operation which would have been ideal road for them - ( and passengers).

Management were less keen until the massive improvement to the service after RMLs replaced DMs, showed up on the performance data. Hugs all round for the reduction in complaints & all round improvements in performance from both operating and maintenance perspectives. Then using RMC/RCLs was raised as a more serious possibility. Initially for very early turns for faster timings and a warmer bus - except I've never been in a warm RMC! In the event only the X15 used RMCs and RMAs.
The 607 had to wait a good few years to appear, and by then RM/ Crew operation was history on the west London trunk route.

Likewise, the RMA staff bus was also popular, especially in winter, but it was notorious for having lousy brakes which I think plagued a few others at other garages.
I think it may have been a different spec brake lining for those faster BEA vehicles, and that somehow that spec got lost and downgraded to the standard type for service RMs which use lower speeds but more frequent applications. Never did get to the bottom of that one.

They both went out on a few rescue runs by choice rather than necessity. I seem to recall that one or two RMCs had the air suspension replaced by the standard RM coil set up But the first two were still green and still with Air.

They would sit low at the rear so could not really be moved until they had pumped up. It was risky as the platform could catch any undulation on the surface. Parking up had to be careful to not overhang any stop blocks

One of the issues was an equaliser/ regulator located under the rear junction which would ensure the bus sat level. If those failed then the bus would sit too high on one side and too low the other and lean over. A very easy fix though, to replace the smallish component.

Properly set up with all the other parts of the suspension set and greased and with the Dunlop airbags in good order and correctly fitted, this gave a superior ride.

I cannot remember a second air tank But there must have been. I certainly never had to attend to any issue with them, but I would have been supervised if that had occurred at that juncture in time.

Presumably someone will have a drawing / specification for the original set up and later mods.

So sorry Brian, more anecdotal than helpful, unless I remember a bit more in due course.

Re: RMC air suspension

Thanks Jack, at least you have confirmed three things, there was a levelling valve, they have a second tank and you can get gears even if the bags are down. I think the non return valve in front of the rear tank is to stop the suspension tank drawing air from the gearbox tank. Unfortunately the RM Manual doesn't cover RMCs.

My bus number (if any): RTL 960, RMC 1458, RM 1585 and several RTs

Re: RMC air suspension

There is a danger of bursting the bags if the bus is driven before the air has built up to inflate the airbags fully. With two tanks the buses take a lot longer to build up air as well.

Re: RMC air suspension

Thanks Roy I think in the case of the owner we are trying to help that may be the case. He was stopped by the Police because his rear end was down so to speak :)

My bus number (if any): RTL 960, RMC 1458, RM 1585 and several RTs

Re: RMC air suspension

The same as HGV trailers if they are pulled without the airbags inflated the rubber can get pinched and stressed when they go over bumps making holes in them and ruining the seals.

My bus number (if any): RML2747

Re: RMC air suspension

Hello everyone.

I can confirm there is 2 air tanks and takes longer to get ready from scratch, on average mine takes about 30 mins.

There is 2 levelling valves, one for each side. There is either side a test valve for each one to check air is getting to them.

One problem i've found is the linkage arm which is made from either a fabric or rubber depending on the mods and either end can break meaning that valve cannot do its job and causing it to lean to one side.

I could do with a new pair of airbags for mine at some point.

My bus number (if any): RMC1490

Re: RMC air suspension

Thanks Robert
I believe the shortage of spares for the RMC air suspension led to a lot of RMCs being converted to coil springs by LT when they re-purchased them from LCBS.

My bus number (if any): RTL 960, RMC 1458, RM 1585 and several RTs