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Hills

Hello Gents (and Ladies) Has anyone had problems with a Cummins C series and hill starts in 1st gear with a load on board the bus? It has happened to me a couple of times now my bus does not like steep hills with an almost full bus. It has a rebuilt fuel pump, new flywheel, rebuilt gearbox.It gets to a certain point on the hill, and will not move! Any advice would be greatly appreciated

My bus number (if any): RML 2353 MB 306

Re: Hills

If you have anything other than a standard 5.22/1 rear axle ratio this is hardly surprising.

How steep is the hill and have you tried working out your ACTUAL gross weight? Passengers don't weigh 10 stone, 63.5kg any more. Far more likely to be nearer to 14 stone so roughly 90kg. That is roughly an extra 2 tons of blubber, so the bus is getting on for 15t all up. In service the buses needed 1st gear to pull away from the lights at Wellington Arch and you'd hardly call that a hill.

If the flywheel oil level is OK then get a compression test done. Check full throttle at pedal equals full throttle at pump and that engine stop is fully off. Check that brakes are not binding. Check the air filter is not choked.

Re: Hills

I think the current EU standard for the average passenger is now 66kg. It was increased a couple of years ago after many coaches were found to be overweight when filled with "average" passengers and luggage, though luggage shouldn't be a problem on an RML. Mind you, how many tinnies do your Aussie passengers take on board with them :) ?

But as roy says, check the pump is opening fully. sometimes you may have an air leak on the throttle dip valve if it's still fitted. On the Iveco engines, their problem is the linkage is set up wrong and the slightest bit of wear on the pivots will cause loss of power. I've dealt with several like that over the years.

Was your pump rebuilt to LT spec or Cummins spec? Mine was done to Cummins spec to 2400rpm and flies along at near lorry speeds and will go up Wrotham Hill on the M20 with little noticeable loss of speed when empty.

My bus number (if any): RML2532