New Atkinson cab designed fo maintenance accessibility
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ATER the spate of new cabin designs featured at the 1964 Commercial Motor Show and since, it is natural that there will be little new in this respect at this year's Show. But one company—Atkinson Vehicles Ltd.—is to feature a new cab with many good features and a number of other exhibits by the company will also be of interest. The cab will be shown on a six-wheeler designed for export and this chassis will also have the latest David Brown 10-speed gearbox and a new Kirkstall front axle. Other exhibits will include a twin-steer 32 ton gross train weight tractive unit fitted with the new Gardner 6LX13 diesel engine and other show models will have spring-brake actuators and lock-type actuators that are available from Westinghouse.
Although there will be interest in many of the Show chassis the cab is possibly going to be the major item. Access to the engine for servicing, visibility and interior spaciousness have been given a good deal of consideration in the design of the unit and the fittings used are to a high standard. The cab is constructed in two distinct halves, a sub-frame consisting of a steel-angle framework with sheet-steel panelling and an upper half which has a timber frame and plastics panels. The dimension from the front bumper to the back of the cab is 5 ft. 0.75 in. and from the centre line of the axle to the rear of the cab is 2 ft. 5.625 in. The unit is designed to be used on chassis having Gardner, Cummins or Rolls-Royce engines and to be produced in right-hand or lefthand drive versions.
One of the most striking things about the unit is the height of the floor above the ground and in the unladen condition this is 4 ft. 8 in. With an interior height of 5 ft. I in. maximum this makes the overall height unladen about 9 ft. 10 in. but in spite of this the cab looks well proportioned. Access to the cab in spite of its high floor line is not diffic and two steps are provided, one in the panelling behind the fr, wheel at 1 ft. 6.25 in. from the ground and the other at the rear the cab 3 ft. 2 in. above ground level. Grab handles on the r of the cab and on the door itself help from the access point view. One important advantage in having such a high floor lin, that there are no wheel arch protrusions in the cab and the hei of the engine cover is only 1 ft. This makes for a roomy intei and with the width of the bonnet only just over 2 ft. access acr the cab is good.
The windscreen is in three pieces with a large central sect 3 ft. 2 in. by 6 ft. 2 in. wide and at its sides there are narrc section pillars and curved quarter lights. The central sectior slightly curved—the radius is 28 ft. There are two large wind( in the flat rear panel and these come to within about 6 in. of cabin sides. The windscreen has a rake of about 8 degrees.
The new cab has been designed to be used with ZF integ power steering and this unit is operated through a universa, jointed shaft which has allowed a freedom in the positioning E angling of the steering wheel. Because power steering is plant for models accepting the cab a small-diameter steering whee used. The instrument console is mounted in front of the driver a panel at an angle of 45 degrees and the instruments are arrant for maximum visibility through the steering wheel spokes. 1 surround of the console is shrouded to prevent reflection of instrument illumination in the windscreen.
Heating and demisting equipment is incorporated in the ( as standard, in the Show model a Smiths 4.36 kW unit be fitted. But it is planned to fit a 7 kW unit when the cab goes ii production. There are five demisting outlets for the windscre three of them covering the centre section, and fresh air ventilat is provided by Smiths Spherivent units located on the vertical fl of the dash, one at each side. These can be used to direct where it is wanted. Windscreen wiping equipment consists o central air-pressure-operated motor with the drive throb linkage to top-mounted wipers. The offside arm is 18 in. and t. on the nearside is 20 in. long and both blades are 20 in. long. 1 roof and floor of the cab are insulated with 2 in.-thick Fibregl
I rubber mats and a padded bonnet cover is provided to mini T engine noise.
Chere are a number of features in the cab design which have n aimed at giving good access to the engine for maintenance. rear wing sections on both sides are hinged and allow a man get under the cab and close to the engine. Because most work be done from the left-hand side there is a folding trap in the nthere and with this raised and the engine cover up a man can 7k on the engine with as much freedom as on a tilt-cab design. lovel touch is that a small metal platform has been designed to over the front-axle kingpin to act as a seat or a leg rest. Even hout side access most points of the engine can be reached by ;ing the full-width engine cover.
iimilar thought has been put into getting at the front of the me and the front grille can be removed through eight quick:ase screws to reach the radiator. The radiator itself is easily lovable, and is mounted on a substantial tubular cross-member .ch itself can be taken out readily for removal of the engine. k suspension-type driver's seat is fitted as standard and this is )1. mounted whilst the seat for the mate is carried on a bracket ged to the rear panel; this is done so that the seat can be ;ed out of the way of a man working on the engine. A further ful item for the driver is a built-in document box at the rear the cab, behind his seat.
[he chassis on the Atkinson stand to which the new cab be fitted is a six-wheel-drive tractive unit designed specifically export and suitable for operation up to 45 tons gross train ght. The engine is a Cummins NH 250 which has an output of ) b.h.p. gross and the recently-introduced David Brown 10-650 Lrbox is used. This has a bottom ratio of 8.94 to 1 and an overve top gear of 0.758 to 1. The rear bogie is a Kirkstall T48 unit h a reduction of 6.9 to 1 and the drive between the spiral'el-spur double reduction driving heads is through a third .erential which has an air-operated lock. The ZF poweristed steering in the Show model is the Type 25.
The new Kirkstall front axle used on this chassis has a capacity of 40,000 lb. (6.3 tons) and has a wider track than previous designs, this dimension being 6 ft. 8.75 in. But it allows an improved lock with the bigger tyres required currently. The show chassis has 11.00-20. Another interesting fitting on this chassis is MGM spring brake actuators at the rear bogie to provide for the parkingbrake function.
The twin-steered tractive unit to be featured by Atkinson is not a new design, examples having been in service since earlier this year. But the Show model is new in that a Gardner 6LXB engine is used and this drives through a David Brown 657 overdrive gearbox. An interesting fitting in the brake system of this chassis is Westinghouse lock-type actuators at the second steering axle and the driving axle. These consist of dual-diaphragm chambers and in an extension to the casing there is a locking mechanism which can be brought into action to hold the brakes in the "on" position when the air pressure is exhausted.
On a 30-ton four-wheeled tractive unit with Cummins NH 220 engine to be shown there will be a new-design rear suspension developed by Atkinson. The springs are mounted on top of the axle casing, the first time the company has done this on a heavyweight tractive unit. This has been made possible by the use of a wider axle and, even allowing for the springs to be located outside the frame, the overall width across the side members is kept at 3 ft. 2 in. The Cummins engine in this chassis will drive through a ZF 6-75 overdrive gearbox to a Kirkstall axle.
The final two exhibits to be seen on the Atkinson stand have Gardner 6LX engines and these are a 22-ton gross six-wheeler and a 24-ton gross eight-wheeler tipper. The main difference between the two chassis mechanically is that the six-wheeler will have a Centrax CVTD220 hypoid-bevel-drive rear bogie whilst the eight-wheeler will have Kirkstall T48 bogie. Another difference will be that the six-wheeler is to have ZF power-assisted steering and the eight-wheeler a Marks cam-and-double-roller box.
AJ.P.W.