Leyland Octopus at 30 tons gvw
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by Stephen Gray photographs by Dick Ross
IN SEPTEMBER last year Leyland introduced its latest version of the Octopus eight-wheeled chassis which, it is claimed, is 500kg (10cwt) lighter in chassis cab form than its nearest competitor.
This weight advantage is a boon for long-distance general haulage. It can carry a similar payload to that of a 32.2 tonnes (32 tons) gcw artic, but it can be driven by Class 2 hgv licence holders. Of course, there are disadvantages. The load platform is around 3m (10ft) shorter than the average artic trailer, and the Octopus's eight wheels, combined with a fairly poor lock makes manoeuvring more difficult than with a tractor-trailer outfit—for example up to a loading bay.
However, to see how useful the Octopus is as a general haulage vehicle, CM has been testing it over the Scottish test route. The vehicle supplied for trial was fitted with the turbocharged Leyland 511 engine and the optional higher rear axle ratio of 6.25 to 1. The fixed head six-cylinder engine develops a useful 172kW (230 bhp) at 2,400rpm which gives the Octopus a very good power to weight ratio, A Fuller RTO 609 nine-speed gearbox transmits the power to the rear axles which incorporate a lockable third differential.
Overall fuel consumption for the 1171.9km (728.2 miles) of the test route was 37.7 litre/ 100Iun (7,5mpg)—even better than the figure of 38.7 litre/ 100km (7.3mpg) obtained a year ago during CM's road test of the Leyland Buffalo, which was carrying only 300kg (6cwt) more than the Octopus. When it is realised that the Octopus completed the course 29min faster than the Buffalo, this fuel consumption is very good indeed.
Without doubt the Octopus is a motorway vehicle. It cruised happily at 96.5km (60mph) on M6 and rarely dropped below 641cm/h (40mph) even on the more hilly sections. Fuel consumption was better on this section of the test than for some of the A roads. This was probably due to the higher axle ratio employed. Although a lower ratio of perhaps 6.4 to 1 would probably improve the figures over A roads, motorway consumption would suffer. A further indication of the possible need for a lower axle ratio came when the Octopus failed to start on a 1 in 5 gradient although it had performance to spare on the motorway.
Leyland offers an axle ratio of 6.933 to 1 on the tipper chassis, but this is obviously far too low for haulage work. The Fuller gearbox seemed well suited to its application, but as the vehicle had only covered 3,000 to 4,000km (1,866 to 2,488 miles) it was hardly run in and was very stiff to use, becoming momentarily stuck in top gear on occasions. Nevertheless, by choosing the engine revs carefully, smooth changes could be made throughout the other ratios, and the box improved as the test progressed.
No problems were experienced on hill climbs. The Octopus took hills, such as Carter Bar in its stride, when the lowest gear needed was fourth and a speed of 33.8km/h (21mph) was maintained throughout. Particularly steep hills on the route through from Rochester to Al meant resorting to first gear, but to be fair we were baulked on more than one occasion by slower moving traffic and road works.
The Octopus has a split cir
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cult air-brake system which provides both primary and secondary braking. Axles one and three and two and four are braked together. The parking brakes are by means of spring brake units on the second, third and fourth axles.
During our brake tests at MIRA the vehicle pulled up squarely every time, However, repeated use on the steep downhill parts of the test route produced brake fade and smoke from the drums, indicating that perhaps an exhaust brake is called for —at least as an optional extra. The park brake was more than capable of holding the vehicle on a l in 5 slope, although the gearing prevented the vehicle from restarting on this gradient even in crawler.
Ride and handling
On the ride and handling section at MIRA, the Octopus drove well. No nasty moments were experienced even when travelling quite fast over the adverse camber sections. The power steering, which is by means of an integrally powered box with an auxiliary ram on the second axle drag link, proved both positive and light. However, power assistance diminishes rapidly to virtually nothing when the engine is ticking over, making it necessary to continually "blip" the throttle when manoeuvring at low speeds in order to maintain control. The power steering is also noisy when the wheel is turned, and this is probably caused by fluid moving in the pipes.
Although the turning circles are big, no problems were experienced while on the road, but parking involved several shunts when turning in between other vehicles.
The Leyland ergonomic cab has been around for some time now, and its age is showing even in the updated form fitted to the Octopus. An instrument binnacle in front of the driver is set too flat for easy instrument reading and reflections through the windscreen make the situation worse.
The whole interior has been revamped on the latest Octopus with ABS plastic trim all round and a ventilated headlining in the same material. Seats, now faced in brushed nylon, remained very cool despite temperatures nearing the 90s on the road test.
Grab handles are fitted for the driver and passenger, but to enter the driving seat it is necessary to reach for the steering wheel.
The engine cover intrudes a great deal into the cab making the provision of a third seat impossible. More attention has been paid to the sound insulation on this latest vehicle, particularly around the engine cover.
Certainly the Octopus was reasonably quiet even at speed. The slide-up door windows were stiff and difficult to operate and had fiddly locking mechanisms. Probably the worse feature of the cab layout is the position of the parkbrake lever which is situated close to the off-side window on the instrument binnacle.
Instrumentation includes front and rear reservoir air gauges and a combined oil pressure and water temperature gauge as well as a useful rev counter. Our test vehicle came equipped with a tachograph.
Visibility from the driving seat is good although the large quarter lights can partially obstruct the driving mirrors, in certain positions.
Although the Leyland has a hinged lift-up panel over the engine, most servicing operations can be accomplished only by tilting the cab. This is more easily said than done as the rear of the cab is located by two bolts and nuts which are not really very accessible.
The test vehicle was fitted with an optional hand-operated hydraulic tilt mechanism which saves struggling with the heavy cab. As the steering column and instruments stay with the floor when the cab is tilted, it is necessary to remove the driver's seat otherwise it would come up against the column and prevent full tilting.
The Leyland driver who came on the trip found it easier to take the seat out if the steering wheel was removed, although this is theoretically unnnecessary. An over-centre catch mechanism keeps the cab in its tilt position which is only to an angle of 30 degrees.
By using lightweight components, such as a pressed steel rear bogie assembly in stead of cast iron—Leyland has produced a haulage vehicle which can compete in payload terms with the maximum capacity artic which can be legally used on the UK roads. From this point of view it will appeal to operators who do a lot of motorway work with smaller but heavy loads.
It's a pity that our test vehicle had a few very minor faults, some of which were due to assembly, For example, no ashtrays were fitted—although Leyland assured us they are on production vehicles—and screws were missing from the overhead storage compartments which caused them to rattle and squeak. Nevertheless, at a chassis cab price as tested of £15,540 the Leyland represents good value for money.