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NO LONGER A PANDORA'S BO)4

8th March 1986, Page 46
8th March 1986
Page 46
Page 46, 8th March 1986 — NO LONGER A PANDORA'S BO)4
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Since it took over the license to manufacture the Maxwell automatic gearbox, Avon has been eradicating the bugs which plagued its early history. Bryan Jarvis reports

UNRELIABILITY of automatic gearboxes in buses has long been a source of great irritation to fleet engineers and accountants. so when the Maxwell transmission arrived on the scene five years ago it seemed like good news. Unfortunately, serious teething problems halted its progress.

Now, two years after Avon Maxwell Transmission acquired the licence from the Brockhouse group to develop and manufacture it, the Maxwell box looks set to realise its true potential.

General manager Keith Foulds and his management/development team spent most of last year strengthening production gearboxes and dealing with associated problems under normal warranty arrangements.

Many of the earlier gearboxes had porosity defects but Brockhouse cured this fault and they are now cast in a much higher quality aluminium alloy.

The original oil pump, which was mounted within the sump casing, also used to be inadequate and unreliable. Clutch packs used to fail through oil starvation arid pump flow rates were often suspected. Dowty pumps with suitable flow rates replaced them and are mounted externally against the rear endcasing and driven by the central input shaft.

Yet another problem was the shearing of the bolts holding the input reduction gearing, which resulted in expensive downtime. A dowel and tab washer is now used as a remedy and a single-piece forging is not far away.

"With more development of the original design all of these faults could have been avoided much earlier. It's a real pity," says Keith Foulds' "It's a very good box which earned a bad reputation in the beginning through one or two weaknesses. It is after all one of the simplest automatics on the market, has a built-in retarder and offers easy clutch maintenance." .

Since taking over the Maxwell transmission Avon's main priority has been to improve the original design and look after existing users. So far, the company has manufactured more than 115 of the latest units, replacing most of the faulty pre-production ones (not all of which were failures).

There are 123 transmissions now in service throughout the UK with bus companies including London Bus, the Scottish Bus Group, Cardiff, Manchester and South Yorkshire Passenger Transport Executive. Thes seem to be proving satisfactory.

ATYPICAL long-term user of Maxwell boxes is Warrington Borough, which has several Leyland Olympians with them in its mixed fleet. They developed most of known defects and had long periods { downtime. Now the buses are in ser% with modified boxes.

Transport manager George Hurst, who was disappointed in the original units, is sufficiently confident in the r production version that he has ordere two more. "Although it is still early days yet, Avon seems to have got it right at last," he says.

Avon has also produced installation for Bristol VRT, Dennis Domino, Dominator and Falcon buses, as well Ailsa B55s, MCTs and Leyland Fleetlines and Leopards.

Current developments include a fiv. speed box and a new side-drive. Any truck applications are ruled out for th. immediate future.

Keith Foulds enthuses about a new clutch start built into a Dennis Domir It reacts easily and can be matched to suit any engine's characteristics. The first one is going to Manchester Bus a other are due for a Trent Olympian, London Metrobus and Bristol VRT ir Cardiff.

The company is also looking clos0 at the retrofit market, particularly wit Olympians where the Maxwell can be installed for around 0,600.

Another likely sales area is the midibus market. Currently, Avon Maxwell is discussing applications wit lvcco along these lines.

There are distinct possibilities overs. too. The company is looking closely a the Far East (including Korea) and America. where airport and schools especially could offer vast opportunitil "Avon does not need a huge


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