There is a lot of talk about body swaps and identity changes so maybe this will help. It includes a part of a previos post atht I made.

First off. There was/is NO such thing as a body swaps. Its a totally misleading term to use about the way that LT managed its bus overhaul and float programme.

Buses had a log book that recorded the registration plate and chassis number. LT was allowed by the D of Tp to change the chassis number on its vehicles at overhaul following recertification. The “chassis” on an RM as most know, was made up of an A frame and B frame, these were individually numbered and identified in records as “the chassis” and LT retained records of the component parts, ie which A and B frame numbers made up a "chassis" for the period between overhauls. In some cases where the A or B frames had to be changed due to accident damage so some chassis did not even have corresponding A and B numbers, I recall the overhaul programme showing something like for example RM 1683 body B 558 - Chassis A 108/B1257

RMs came out of the paint line at Aldenham Works with just three identities. Body number; A frame number and B frame numbers. They gained a fleet or stock number and the corresponding registration plate numbers on the finishing line. The chassis number was also added to the bus and that tallied with the stock number of the bus that would leave the works. The “chassis” number ALWAYS tallied with the bus number and that was identified on a brass plate riveted on the bottom of the cab bulkhead window when the bus was on the Finishing Line

The origin of the body of an RM is easily determined by its body number which never officially changed. This of course determined its original stock number and enabled its various identities as other numbered buses to be recorded and tracked for the purpose of modifications and the type of electrical equipment fitted

Maybe an example will help remove the mystery and some of the myths that seems to have built up about identity and body "swaps"
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In all its forms RM 300, WLT 300, had chassis RM 300 but after an overhaul what that "chassis" was made up of could have been literally any A and B frame combination, so even after its third overhaul the “new” RM 300 coming out of the works would still be RM 300 WLT 300 - Chassis RM 300.

But what really constituted RM 300 after its various overhauls?

At its first overhaul RM 300 (originally body B 300; chassis RM 300 (made up of A/B 300) acquired Body B231, it still officially had chassis RM 300 which was originally A/B 300 but that was now perhaps A/B 1222.

The original RM 300 went onto the Works to be overhauled and emerged later as RM 323 WLT 323 chassis number RM 323 but this " chassis” was not necessarily made up of the original A/B 300 combination in fact it was almost certain that it was not.

So after its second overhaul RM 300 left the works made up of Body B239 and with maybe A/B 293 but the chassis number on the brass plate was still RM 300 to match the registration plate and log book details.

The A and B frames had AEC numbers originally allocated to these units but as with the RTs and RTLs before them, LT ignored these numbers completely after delivery and gave them their own chassis unit numbers, with the RMs these were the A and B numbers identified by a brass plate on the unit.

Records were certainly kept of the buses that carried the various A and B frame numbers and which chassis these units were part of in the various identities, but the problem is the number of different possible past identities makes the history of any LT bus that went through Aldenham very complicated to follow because after just 3 overhauls with each constituent part of the original bus body, A frame and B frame all having a second and third identity as parts of different buses, you can see that tracing the history of just one bus can be quite complex to follow not even thinking about that any one bus probably had any number of engines, axles, gear boxes and changed panels throughout its life!!

My bus number (if any): RTL 960, RML 2667, RM 1585, RMC 1458 and 14 RTs

Brian

Thanks for shedding some light on what's a highly complex yet fascinating aspect of LT practices.

I have a couple of questions. First, were the A and B frame numbers (as carried on the brass plates on the frames themselves) allocated to the RM's at first overhaul i.e similar to the RT Chassis Unit numbers. Secondly, once allocated to a particular A or B frame did these A and B frame numbers normally stay with the respective A and B frames?

Ive posed the second question as I'm a little puzzled by the A and B frame numbers allocated to my bus (RM1699). Prior to replacing the B frame about 6 years ago (that meant the B frame number was changed), the A and B frame numbers were A/B 1039. This was numerically close to the body no B1043 that the vehicle carries. However I think the origin of my A frame is from RMC1516 - I can tell this from the code R2RH1512 that's stamed on the nearside forward edge of the A frame. It's puzzling that the chassis from RMC1516 would have been allocated an A frame number that's numerically significantly lower since it would have passed through Aldenham a year or so later RM's in the early 1000's sequence.

So maybe there was some swapping of the A and B plates between chassis/sub frames. If this was indeed the case with the RM's, I wonder did the same thing happen with the RT's?

Any further light that you're able to bring to bear on this would be most welcome!

My bus number (if any): RM1699 - Eastbourne Regent V 69

Hello,

thanks for these great information!

Now I understand why the brass plate on the A frame of our RM98 shows "RM169 A" and the one on the B frame "B169". On the pages of Ian's Bus Stop you can read that RM98 got the body of RM169 in October 1980 and retained it at its last overhaul in November 1984. Today the A and B frames of RM169 are fitted - so RM98 doesn't exist anymore but RM169 is back to life!

So the LT fleet numbers are really just numbers that doesn't tell anything about the real identity of the bus.

Paul

My bus number (if any): RM98

Were the A and B frame numbers (as carried on the brass plates on the frames themselves) allocated to the RM's at first overhaul i.e. similar to the RT Chassis Unit numbers?
Steve, I am not too sure about this one, but I believe that they were allocated on first overhaul as all the numbers tallied up to then, e.g. RM 299, B 299 A/B 299

Secondly, once allocated to a particular A or B frame did these A and B frame numbers normally stay with the respective A and B frames?

Yes. As far as I know numbers remained constant. Even when A frames were completely wrecked in accidents as some were and the majority of the major component parts were “scrapped”, when the A frame was rebuilt with new or repaired parts it took the unit number of the original A frame but the parts were repaired or replaced for use in other frames, in the same way that chassis beams were with RTs and RTL chassis. This practice may explain your number differences as the side member from the original A frame could have been replaced with a part of another frame. Maybe coincidence, but I remember that one of the RMCs had a nasty fatal head on accident with a car in 1965 that tore off the O/S wheel and twisted the front boat and damaged the A frame quite severely, so a new A frame was built in the chassis accident shop and the surviving mechanical units from the original frame like the engine fuel pump and starter etc fitted to the newly built A frame. The original frame was taken out of the bus and dismantled and the parts from it no doubt were straightened or repaired for use on another frame.

Paul
The fleet number was the means of identification at any one time even though the component parts of that fleet number in terms of body and chassis may have changed four or five times during its lifetime.

My bus number (if any): RTL 960, RML 2667, RM 1585, RMC 1458 and 14 RTs

Thanks Brian for answering my questions. It may just be that my A frame did come from that RMC you mentioned that was involved in an accident in 1965. It may have somehow become A frame number A1039 that would have been in Aldenham for its first overhaul in 1966.

I wonder whether one day the records will ever come to light!

My bus number (if any): RM1699 Eastbourne Regent V 69

Today I found some more information about the history of RM98.
The A frame is numbered as "169A" as written before. The chassis no on the nearside part of the A frame tells us that is was first used in RM146 (R2RH145).

Very confusing to know that the fleet number is just a number that doesn't tell us the real identity of our bus. In Germany every vehicle has a unique ID on its frame or on another unremovable part. So a registration is always connected with the chassis no.

Paul

My bus number (if any): RM98

"Very confusing to know that the fleet number is just a number that doesn't tell us the real identity of our bus. In Germany every vehicle has a unique ID on its frame or on another irremovable part. So a registration is always connected with the chassis no."

It is very confusing Paul, but only for LT buses. Normally vehicles in the UK have the same unique chassis number that is tied to the registration plate but the registration plate can be changed in the UK as personalised plates are available and in Europe a lot of cars change their number plate for example in Germany, France and Spain they have to be changed if you move to another part of the country, LT just changed the chassis plate!!.

In the UK LT were allowed to change the chassis numbers on their buses due to the unique overhaul and changing of bodies that was done on overhaul. The chassis number had to tie up with the registration book details for a particular registration plate so as few if any buses came out of overhaul with the original chassis, the chassis plate carried a plate with the original chassis number of the registration it now had, t was not the original chassis that it was fixed to, just one like it!! LT had a record of which chassis was on each bus as all chassis units had LT serial numbers.

My bus number (if any): RTL 960, RML 2667, RM 1585, RMC 1458 and 14 RTs

Interesting reference to RMC 1516, I owned this bus a few years ago. It had B1519 along with A frame 1519, however the AEC chassis number was for a Leyland engined RM begining 2RH2, can't remember what the exact number was though. Also i seem to remember that RML 900 has the A frame from an RMC although it carries the brass tag A 900. I think that the A frame number stamped on the brass tag attached to A frame is the CU number given by LT & in some cases does not relate to the AEC chassis number at all at all.

Very often the A and B frame numbers do match the body number carried on a perticular vehicle. for example RMC1477 now woned by Timebus but once owned by a near neighbour and friend of mine, carried Body B1456 and A/B frame 1456. This is logical since the bus went through only one body change at Aldenham in 1967 when it acquired B1456. Co-incidentally the AEC chassis number was R2RH1252 that originated from RM1256 that was a leyland RM, similar to RMC1516!

However I've noted that other RM's that have experienced several body changes often (but not always) seem to have matching A and B frame and body numbers. For example, RM581 (that once used to share a garage with RM1699) carries body B504 with matching A and B frames 504, although the original AEC chassis was from RM474. Given that it is most unlikely that A and B frames 504 would have stayed together with body 504 throughout 4 or so overhaul cycles, its puzzling why the A and B frame and body numbers should match up!

My bus number (if any): RM1699 - Eastbourne Regent V 69

Just to be clear on this: Brian's post relates to the Aldenham overhaul process. The start date from when LT commenced swopping registrations for tax purposes as part of the overhaul process is in the literature somewhere and it obviously ceased when the full overhauls at Aldenham stopped. It applied only to the major classes - the RT and RF families and Routemasters - but within these some small sub classes and special vehicles were excluded.

I do not know the situation with Routematsters but the published RF family overhaul history shows that the majority of vehicles retained the same body and chassis at overhaul but changed identity.

It is often stated that body swops occurred because the bodies took longer to overhaul than the chassis, but I think this stems from LGOC publicity from the 1920's rather than a real understanding of what LT did at Aldenham in particular! If this was really a determinimg factor at Aldenham then every bus body overhauled in the normal course of events would have a different chassis to that it came in with, which clearly was not the case.

Prior to the full Aldenham overhaul process coming on line there were body swops in the true sense during Chiswick overhauls.

Good clarifying points Andrew, but the RF situation was not quite that of the RT and RM families where for an RT or RM to leave with the same chassis and body combination was indeed a rare event and only achieved deliberately for GB plated vehicles or on small sub groups of buses like some of the original Green Line RTs that had saloon heaters fitted so the chassis had to wait for a suitable body often the one it came in with. It was the small numbers of buses going through the works at any time that reduced the possibility of a body getting mounted on another chassis as was common with the RT family, but as you say, the RFs were still subject to the same system whereby another bus with the same number was sitting in the Licensing Shop waiting to go out when the bus arrived for overhaul.

LT certainly believed that overhauls would take longer for bodies well into the 60's despite events showing that this was not a real problem, but there were originally 15 additional RT bodies purchased in 1954 and 2 additional RM bodies purchased in 1963, 9985 and 9986, which became RMs 162 and 90 respectively, but in due cause making bodies B294 and 311, both overhauled but not mounted onto a chassis the floats and they sat in Aldenham close to the paint line for a long time, ending up as RMs 1768 and 500 replacing fire damaged bodies.

My bus number (if any): RTL 960, RML 2667, RM 1585, RMC 1458 and 14 RTs