What Chassis Is This?

[AdamH]

One for the true Midland Red experts...

I was sent this photograph some time ago of a BMMO chassis and it's puzzled me as to which model it was from. The "SOS" radiator would suggest it is pre-war, but the under-floor engine layout is clearly post-war. An early S6 maybe but with an older spare/unused radiator temporarily fitted? The batteries are at the very back and I was under the impression they were between the axles on the S6 but I could be mistaken on that. I also though it could be one of the ex-REC rebuilt as BMMO S1-S4 prototypes in 1942-1944, but then I noticed it has a manual gear stick... Didn't they all have Cotal or Wilson auto/semi-auto gearboxes?

And if you're really good you can tell me the names of the three men!

[MattW]

Looks like a special lightweight sports version to me

[TimBrown]

One for the true Midland Red experts...

I was sent this photograph some time ago of a BMMO chassis and it's puzzled me as to which model it was from. The "SOS" radiator would suggest it is pre-war, but the under-floor engine layout is clearly post-war. An early S6 maybe but with an older spare/unused radiator temporarily fitted? The batteries are at the very back and I was under the impression they were between the axles on the S6 but I could be mistaken on that. I also though it could be one of the ex-REC rebuilt as BMMO S1-S4 prototypes in 1942-1944, but then I noticed it has a manual gear stick... Didn't they all have Cotal or Wilson auto/semi-auto gearboxes?

And if you're really good you can tell me the names of the three men!

I had an idea that a similar photograph existed in one of my reference books and found it in Midland Red History Part II from 1940 to 1970 by Paul Gray, Malcolm Keeley and John Searle. An off-side shot is shown on page 22 with a note that it was either (type S1) 1591 BHA 1, (type S2) 1942 CHA 1, or (type S4) 1944 CHA 3 which all had a ZF Aphon 4 speed constant mesh gearbox fitted. Apparently, (type S3) 1943 CHA 2 was the only one of these four experimental prototypes to run with a Wilson preselective gearbox.

As for the names of the three development engineers - that remains a mystery for now!

[AdamH]

Thank you Tim,

I have looked at that photo and I would agree it is the same chassis, just photographed from a different angle. I have also looked at a PSV Circle / Omnibus Society book from 1959 which has quite a bit of detail on the buses but basically says all four had various two-pedal setups when built in 1935/6 but all except the S3 were converted to manual during the war when they were rebuilt... Hence my mistake, I was under the impression they all retained their original gearboxes.

I would hazard a guess that the photographed chassis is the first example, BHA1. Unlikely they would have made a fuss about the second and third one etc!

Matt... Chassis were often driven on the public highway like this, being delivered to the coach builder to have their bodywork fitted. I wonder if anyone ever pulled up at a bus stop, just for fun?

[MattW]

I bet someone did

[Severnside]

This is the S1, BHA 1. It was the only one of the underfloor engine chassis to have the oil filler on the nearside. Note also it retains the SOS style centre accelerator pedal.

[AdamH]

This is the S1, BHA 1. It was the only one of the underfloor engine chassis to have the oil filler on the nearside. Note also it retains the SOS style centre accelerator pedal.

Someone clearly knows what they are talking about! Thank you.

[Lloyd]

Yes, definately BHA 1's chassis. Note many "standard" components of the time are used - SON radiator (complete with unneeded starting handle hole); complete SON front axle, steering column, and pedals (as far as can be seen). Rear axle looks like a double deck one, but mounted such that the differential is offset to the offside and mounted from the top (in other words, fitted upside down and back to front). Hub carriers and brake gear can be mounted as per normal layout.

It is now thought that LGW Shire was involved in the design of the first undefloor engined chassis, following the problems found with his REC class rear engined ones, and the SOS badge on the radiator supports this. LGWS retired in 1940, probably about the time of this photo, following which Donald Sinclair took the engineering reins as well as the traffic ones, becoming General Manager incorporating both Shire's and OC Power's roles. Sinclair wasted little time having the "SOS" name removed from radiators, replacing it with "BMMO" although some old SOS branded stock continued to be used up - rear half shafts on some S6 and C1 chassis, for instance. In the event the body as built had a concealed radiator, possibly this one, although by the time of later rebuilds of the front end a smaller unit was in use.

Batteries at the rear became the normal position for S6-12 classes, although coaches C1-4 had them in two lockers either side of the entrance door as a luggage boot occupied the rear space.

[AdamH]

Thank you for posting Lloyd.

The prototypes and developments vehicles have always fascinated me.

[MattW]

Its amazing the amount of info people have. Thanks mate!