Prototype Cave-Browne-Cave cooling installation

Many of you will have seen, photographed, ridden in or driven Bristol buses fitted with the unusual Cave-Browne-Cave cooling system. So here’s a photo of one of the prototype buses.

This is Hants & Dorset 1068, a 1940 Bristol K5G carrying an early version of the cooling/heating system invented by Wing Commander T. R. Cave-Browne-Cave. He was Professor of Engineering at Southampton University at the time. The photograph comes from my own collection and came to light while I was looking for images for a new book I’m writing.

In a nutshell, the traditional radiator mounted in front of the engine is omitted and two – smaller – radiators are fitted either side of the destination display. These also act as forced air heaters for warming the upper deck. In summertime, when the saloon heating isn’t necessary, the warm air can be deflected through vents on the sides of the bus.

I’m not sure why the Wing Commander was commissioned to create this system because the traditional cooling system had been working reasonably well for decades previously and indeed continues in the same form to this day. Anyway, his first prototype installation was fitted to a Southampton Corporation Guy Arab. The test went well evidently and the second installation was fitted to a Hants & Dorset Bristol K, as shown above. The front cowl, obviously from a Lodekka, was a later modification because the original front was more obviously based on the standard PV2 radiator shape.

Cave-Browne-Cave obviously sold the idea to Bristol Commercial Vehicles/Eastern Coach Works and it was widely adopted as an option for Bristol LDs and F-series Bristols as we all know. Some more of Southampton’s Guy Arabs were also fitted with CBC, as were a few Bristol Ls of West Yorkshire Road Car.

The new-fangled system wasn’t all that popular with drivers and fitters though. The radiators worked well when the bus was making good progress but if it was well loaded and making frequent stops the CBC system struggled to keep up and a fountain of scalding hot water would erupt from the vent pipe on the bonnet.

Other contributory factors included a buildup of sludge in the system or air locks in the plumbing due to incorrect topping up techniques. Bristol’s own AVW and BVW engines, which were known to run hotter than a Gardner, were also thought to make things worse.

All I can say, having used buses with CBC and without, is that the system has never given me any bother. Even when toiling up some of Somerset’s long hills with a fully laden bus, I’ve never had one boil over.

In other news, this weekend sees a special commemorative event taking place at Exeter Bus Station. Organised by the Devon General Omnibus Trust, the running day is to mark the closure of the Bus Station, which has stood on the Paris Street site since 1964. Now the site is earmarked for redevelopment and the station was to have closed on March 26th but, due to delays in tendering for the construction work by Exeter City Council, the closure has been postponed.

The Westcountry Historic Omnibus & Transport Trust is also involved with the running day and has entered two vehicles plus a static ex-City of  Exeter exhibition bus. I’m due to drive WHOTT’s ex-Western National Bristol LH/Plaxton coach at the event.

I’ve got a wedding duty this Friday with a Bristol L and next week will be doing some assessments of potential drivers for the Crosville heritage bus fleet.

Looking further ahead, English Riviera Sightseeing Tours has added another single deck coach to its fleet and I’m taking it out on its first duty on Easter Saturday.

One comment on “Prototype Cave-Browne-Cave cooling installation

  1. Chris Stewart says:

    John, the photo of APR423 is by R H G Simpson.

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