London Transport RT

The RT bus (sensibly the London Transport version of the standard AEC Regent III product), has a 16ft 4in wheel-base, 6 cylinder 9.6 litre engine with transmission through a four speed air operated pre-selective gearbox with fluid flywheel.  Post war, London Transport de-rated the RTs 115 horse power diesel engines by up to 15% to ensure a longer life. (This preface by Dean Jones).

  London Transport RT with PRV Bodywork.

  Dean Jones, who kindly supplied this photograph of HLW 177, is keen to find a ¾ inch to foot scale “general arrangement drawing” of an RT3 'like the one pictured here in July '05 at the Finchley Carnival.  Can you help?  Please contact me if you can and I'll pass the message on.

  Now a teaser! Spot the difference! Chris Stanley supplied this image of HLW 177 pictured at West Ham garage around 1968/9.

Yes they are both HLW 177 but they sure are different!  Why? Well Park Royal began production of the RT3 during 1946 and this particular bus, LT's RT190 - HLW 177, has a very unusual history. 

Please click here to find out more.

A note about London Transport's Aldenham Works overhaul procedures by Gordon Mackley:

In all fleet operations, legally (and normally) all chassis are aligned with the vehicle registration number and thus to company fleet numbers. However in LT’s case neither the chassis, nor body, necessarily remained associated with the stock number and therefore the registration number.

When LT introduced the Aldenham vehicle-overhaul flow system, it was realised that there could be a large number of buses, with current, valid, road tax licences, undergoing overhaul at any one time. Aligning the overhaul dates with road tax expiry was not practical and therefore LT was potentially faced with paying for more road fund licenses than buses on the road. To prevent this, LT obtained governmental dispensation to transfer registration numbers from one chassis to another (and thus also the stock number).

So, usually, the registration and fleet stock numbers of an incoming bus due for overhaul, were transferred to the next outgoing vehicle of the same type which had completed its overhaul, thus maintaining the continuity of the road fund licence. 

Typically bodies took longer to overhaul and so the next completed chassis received the next suitable overhauled body. Thus, not only did the chassis/body combination change but also the ‘complete identity’ (registration & stock number) could belong to neither.  In the case of the Routemasters, the two sub-frames (running units) were often interchanged and the engine could be exchanged for one of a different manufacture.  Therefore, after overhaul, RM’s were often not the factory-original vehicle. And because many bodies were needed as a ‘float’ in the system, some vehicle identities actually disappeared completely for many years.  (So much for ‘bus spotters’ underlining numbers in their Ian Allan ABC books!)

This approach of course could only be applied to large fleets with interchangeable bodies, such as the RT’s and RTL’s (and later RM’s). The process was not possible for small fleets, with few vehicles being overhauled at any one time.  Occasionally mistakes were made.  And, especially, if buses were delayed going in to the works, two vehicles could be in operation with the same registration and stock numbers.