AEC offered a rear-engine alternative to the Reliance at the 1964 Commercial Motor Show in London in the form of a 36-foot Swift with the AH505 engine. A 33’ 6” version was released in 1966. Interest in lowering floor and step heights by placing the engine at the back of the bus gained momentum in Britain during the mid-1960s and there was a rush among manufacturers to offer a suitable chassis.

AEC Swift ZIB 157 (in experimental livery) at Kingston Depot

Among the pioneer operators in Australia to buy rear-engined city buses was the Department of the Interior. Canberra chose to buy the 33’ 6” Swift and in December 1967, number 121, a Hedges bodied unit entered service, the first of four similar buses bought for evaluation alongside the more familiar Reliance. Although drivers were not keen on the low driving position and the gear linkage, the Swift offered exceptional comfort for passengers on a bus with leaf springs. It also had a wide, low entrance platform and relatively low noise level. It is very rare for a rear-engine city bus to be fitted with manual transmission and these four buses, plus 10 bought in 1969, were among the few manual gearbox Swifts in the world.

Passenger appeal had entered a new era in Canberra. More Reliances and Swifts followed in 1968 and 1969 and then it was decided to buy Swifts exclusively, but this time Canberra moved into the semi-automatic gearbox arena — or to describe it in more specific terms, the Department ordered the AEC Swift 3MP2R, the ‘2’ signifying the fitting of a Wilson semi-automatic epicyclic transmission with Mono-control electro-pneumatic gear selection. The Wilson transmission made by Self Changing Gears was one of the most common gearboxes on British-built buses whilst the Mono-control gear selector switch, mounted on the steering column, had been devised by AEC in conjunction with CAV Ltd. The first semi-automatic Swift, number 156, was bodied by CVI in Sydney and entered service in Canberra on 23 November 1970.

Although Canberra trailed most other cities by many years in introducing such transmissions, passengers were to suffer from the occasional over-energetic driver. The reason was published many years ago in UK: ‘Semiautomatic gearboxes made bad driving so easy’. All the driver had to do was flick a little lever on the steering column from one gear to the next. Although drivers should pause when moving the lever between each gear to permit an appropriate matching of engine revolutions and road speed, one or two over-anxious drivers did not attempt to relate the two variables, with the resultant whiplash affect on the unsuspecting passenger and premature failure of the transmission.

Like other British rear-engine buses of this era, the Swift experienced some engine failures, in the main, caused by the breakage of fan brackets. Some problems were no fault of the chassis design. To quote from Blue Triangle, a history of AEC buses by Alan Townsin, ‘Not all body builders had appreciated the extent to which the body structure of rear-engined single deckers had to cope with the effect of the ton of machinery suspended from the rear overhang of the inevitably flexible chassis — a problem experienced with other similar chasses.

Canberra ran into a body stress problem and some rectification work was necessary on the buses within a relatively short time after delivery. But despite all this, the Swift was generally an attractive bus for passengers. A total of 101 Swifts were bought — 14 bodied by Athol Hedges, 30 by CVI (the last buses built by this subsidiary of Commonwealth Engineering), 37 by Freighter and 20 by Smithfield. This constituted the largest fleet of 505-powered Swifts in the world outside London Transport which bought 838 of the type.

Article extracted from Canberra’s Engineering Heritage

This page was last updated on 11 April 2021

Categories: Fleet