New Volvo six and eight wheel rigids
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TWO new versions of the well-proven F86 model, a 6 x 4 and an 8 X 4 have been announced by Volvo. The new models use a rear bogie which was originated and developed by Volvo's British company Ailsa Trucks Ltd, and which is fully approved by Volvo in Sweden. This new Ailsa bogie enables Volvo to offer a 6 X 4 model operation at 24 ton gvw and an 8 x 4 model at 30 tons gvw.
Double-drive bogie Ailsa Trucks have designed and developed a new double-drive bogie which is used on both the new 6 x 4 and 8 x 4 models. The bogie is not unlike Volvo's own two-spring design, it uses a similar single spring and balance beam layout but differs in that it has a high-mounted spring pack and that the trailing axle is carried on a further lirtage rather than on the balance beam direct.
The spring is slipper-mounted at both ends and located longitudinally by two extra leaves located at the bottom of the spring pack acting as radius arms. The rear end of the spring is connected by a shackle, which is in tension, to the balance beams of the suspension. This shackle is slipper-mounted to the spring and uses a plain bush in the end connected to the beam. The balance beam pivots on taper-roller bearings in trunnion mountings which are bolted to the inside of the frame and linked by a tie bar. The trailing axle is located in turn by "spherilastik" bushes to the balance beams at the bottom of the casing and a torque rod at the top.
Bogie spread is 4ft 114in (1.5 metres) and thus the design load is the full 19 tons allowed under the revised C and U regulations for compensating bogies. The bogie can be used for both single and double drive applications and Ailsa Trucks have announced that an 8 x 2 version of the F86 will be available using the new bogie in due course. This version will use a doublereduction drive axle as standard and a Volvo trailer axle as its non-driven axle.
Four 6 x 4 models The 6 x 4 model will be offered in four wheelbases of 14ft 4in, 15ft 7in, 16ft 1 lin and 18ft 1 lin, but for the time being at least the shortest wheelbase will not be available. The same 6,ton-rated front axle and a 19-ton-rear bogie are used for all nodels and thus all can be plated at tons gvw and as the TD 70C nine gives 192 bhp to BS AU 141a: 971 they can also be plated at 32 ons combination weight.
A new frame developed for use at 1,4 tons gvw uses pressed ide-members which have an 11in X L5in X 0.25in section and an overall vidth of 31.5 in. This basic section is ncreased in critical areas by the tddition of a close-fitting 0.25-thick ;hannel flitch and 0.38in X 2.48in trips welded to top and bottom anges.
Diaphragm brakes are used on the front axle and spring brakes on the bogie axles. The primary system comprises all three axles; the secondary covers the front axle and leading bogie axle only. Parking is by the spring brake units on the bogie. Three-line air braking for a trailer can be specified if required, giving direct trailer braking with the service brake. Total braking area for the 6 X 4 vehicle is 1142sq in.
The cab, engine and gearbox specification is as for F86 but the more powerful TD 100A engine giving 235 bhp is to be offered as an option later.
Power steering is fitted as standard.
Five 8 x 4 models
' Five wheelbases are offered for the 8 x 4 model but only three of these will be available for the time being — 14ft 7in, 16ft 7in and 18ft 6in. The other two, i.e. 15ft I lin and 21ft 2in, will be offered later depending on customer demand. The front axles are rated at 6 tons each and the Ailsa bogie at 19 tons, giving a 1-ton tolerance at 30 tons gvw.
The specification differs from the 6 X 4 version only in its second steering axle. Two Volvo 6-ton drop-forged axles are used, independently mounted on semi-elliptic leaf springs. Double-acting dampers are fitted to the leading axle only.
Power steering is used and a frame-mounted• idler connects the steering to the trailing axle. Brake friction area on the 8 X 4's is 1454sq in. Estimated weights for the 6 x 4 and 8 x 4 are 6.30 and 7.35 tons respectively.