AROnline gets down in the dirt as we take another look at the T45 cab system Leyland introduced back in the early 80’s. Another big seller in the commercial vehicle sector was the Leyland Constructor – a range of 6 or 8 wheel vehicles up to 30 tons GVW. Mike Humble gets into gear and takes a journey back…
The T45 Constructor 6 & 8 replaced the elderly but hard working Bison & Buffalo ranges that had been the stalwart Leyland tippers through most of the 1970`s. Leyland’s chassis engineering had always been excellent so little was changed in this respect with the exception the front most section of the ladder frame to accept its new cab. Much improvement had been made with its braking systems too in recent years, so all in all it very much a case of improving and modernising a decent formula.
Getting to grips with engineering:
The Bison had originally been fitted with the revolutionary yet disappointing 500 series fixed head OHC high speed diesel, but following Leyland modernising its legendary 680 unit into the L11 & TL11, towards the end of its life the Bison became a hard act to follow for operators both fleet and owner driver looking for a no frills, hard grafting machine. Towards the end of the 70’s it became obvious that no matter how reliable it had become, it was dated by design and had its roots from Leyland & AEC designs going back to the 60’s.
The Constructor was launched in 1981 in 6 or 8 wheel format with both rear bogies and front axles along with its chassis being directly carried over from the Bison. Its cab was also based on the Road train or Cruiser in ‘low datum” form on six wheelers and ‘high datum” on the eight, with either a day or sleeper cab. Six wheeler tippers were initially fitted with Leyland’s relatively new TL11 6 cylinder high torque diesels with power options of 181 or 209bhp, higher power options up to 260bhp came later.
Alternative power units:
The eight wheelers could be opted with Rolls 220 or the Gardner 6LXC-T 230 but no other engine options were offered on the six. In order to keep existing drivers happy, Leyland opted not to change too much as far as gearboxes were concerned, opting to use the familiar Eaton 400 which had it roots as far back as the old AEC Mandator. For heavy duty applications the 6 wheeler could be ordered with a nine speed Fuller transmission, while the eight could be fitted with a 10 speed Spicer gearbox.
Its tandem rear drive axles with hub reduction gearing were also carried over from earlier designs and were the source of some trouble on earlier Constructor’s with cases of half shaft failure being known during arduous working. Other problems these vehicles suffered were damage to the bottom of the radiator owing to a poor design of radiator guard on the 6 wheeler and fractured wheel studs were not uncommon, though once various lessons were learnt, the Constructor proved to be popular in service.
Class leading credentials:
Inside the cab, the plush carpeting found in the Roadtrain was substituted for a thick padded rubber flooring to ease the mucking out at the end of the day and a vinyl seat trim could be specified in lieu of the tartan cloth if requested. As the years progressed, the engine options expanded and the eight wheel Constructor could be offered with power from Perkins as well as Cummins, the latter option being very popular with owner drivers. Power ratings varied right up to 300bhp and the Constructor 30:30 was the most powerful tipper on the market for a while.
To cope with the extra power and to keep production costs down, the Albion sourced double reduction rear axles on the 30:30 were substituted with units supplied by Eaton. Fame came to Leyland with the Constructor 6 being chosen as the ‘Popemobile” for his 1982 UK tour, and some readers may well remember the Not The Nine O’ clock News sketch – `I Like Trucking” with HGV licence holder Rowan Atkinson at the wheel of a press demonstrator Constructor. As with the Road train, shortly after the merger with DAF trucks, some product revisions or deletions took place.
Product rationalising & re-engieering:
The Constructor range was re-badged as the 60 series, and at the same time Leyland’s own power unit was phased out along with all the other engine options. A DAF sourced 11.6 litre in line 6 with 300 or 330bhp available, itself a development of the Leyland 680 became the sole power unit. Standard transmission became the Eaton 12 speed twin splitter, while at the rear, the Leyland/ Albion U25 hub reduction axles were replaced by the well known and robust Rockwell type. Production was eventually phased out in 1994 with the launch of a new DAF designed 85 series / CF range, of which CF production continues at Leyland.