E.R.F. FIRST WITH DISC BRAKES
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DISC front brakes are employed on one of the new E.R.F. chassis announced today, and to be exhibited at Earls Court next month. E.R.F., Ltd., Sandbach. Ches., thus become the first commercialvehicle manufacturers to fit disc brakes to a standard chassis. They are installed in the new 54G dumper, which will be seen at the Show in the demonstration park.
There is also a range of semi-forwardcontrol six-wheelers, two examples of which are to be displayed. Modifications to existing chassis include the adoption of parallel-flange frames on all multi-wheelers., the option of the new Gardner 6LX oil engine in the heavy models; a novel dual braking system on certain models; the use of paper-element air cleaners; and changes in the standard cab.
The disc brakes fitted to the 54G dumper hydraulic circuit. Con sequently, a n a i r hydraulic . system h a s been used for the front brakes, whilst the rear brakes are straight airpressure cam operated units. .
The heart of the braking system is the combined servo and air valve, which is mounted on the frame behind the cab and linked to a conventional brake pedal. Pressure on the pedal admits air to the servo, which in turn actuates the hydraulic cylinder controlling the front brakes and at the same time air by-passes the servo and operates the rear brakes directly. The two circuits are " split" for safety. In addition, in the event of a complete failure of the compressed-air supply. the brake pedal will continue to
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actuate the front brakes through the master cylinder in the conventional manner, but without assistance from the servo. A particularly robust chassis frame fabricated from
thick steel pressings is used in the 54G dumper. A new Kirkstall double-reduction rear axle is employed, with underslung springs to reduce the body floor height. The axle has spiral-bevel and spur gears, all the gearing being in the central differential pot, and the overall reduction is 7.01 to 1.
A Gardner 5LW 94 b.h.p. oil engine is employed with a tive-speed, direct-top gearbox, the bottom ratio of which is 7.92 to 1. Mantes cam-and-double-roller steering is fitted and the standard tyres are 10.00-20-in. (14-ply),.mounted on B7.5 wheels with a 6.8-in, offset to guard against trapping stones between the twin rear wheels.
The chassis has an 11-ft. 9-in, wheelbase and an overall length of 20 ft. I in. It will be seen equipped with a forward-control all-steel half-cab and a 7-cu.-yd. all-steel dump body with scow rear end and cab-protection canopy. "Tipping is by twin telescopic rams, giving a 600 angle. The body has a mean length of 11 ft. 3 in. and interior width of 7 ft. 5 in., the overall width being 8 ft. 2 in. Because of this width and the dumper's gross-weight rating of 15 tons
it is fundamentally an " off-highway ." machine. Its unladen weight is 6 tons 12 cwt.
. Three Semi-forward-control Models There are three basic models in the new GSF semiforward-control range, and each is available with either the Gardner 5LW or 6LW oil engine. All are six-wheelers, rated at 181 tons gross when the 5LW unit is installed, and 20 tons with the 6LW engine, and the approximate payloads are 12+ tons and 14+ tons respectively.
The 56GSF and 660SF chassis are offered with a choice of three wheelbases: 17 ft. 6 in., 16 ft. 1 in., or 13 ft. 3 in. On these chassis can be mounted bodies 22 ft., 20 ft. or 15 ft. 6in. long, the shortest being a tipper. Overall lengths are 29 ft. 9 in., 27 ft. 9 in. and 23 ft. 6 in., respectively. The two longer-wheelbase models are 7 ft. IN in. wide, the tipper body being 7 ft. 6-1in. 'wide.
Other than four four-wheelers made specially • at the beginning of the year for brewery work, these new sixwheelers are the first vehicles to be built by E.R.F., Ltd., • without full forward control. The semi-forward layout has been adopted to give equal tyre loadings on the front and bogie wheels, thus enabling the same size of tyre to be fitted to all wheels. At the same time, the front-axle loading is lower than is usual with a six-wheeler, reducing the steering effort and allowing a lighter front axle to be used.
Another important consideration is that the engine farther forward relative to the cab, thus more cab moth is . available and a two-man passenger seat can be installed. The short " snout " in no way reduces forward visibility, it still being possible to see to within 9 ft. of the front bumper at ground level on the vehicle centre line.
The 560SF models have as standard, the Gardner 5LW engine developing 94 b.h.p. at 1,700 r.p.m. and 300 lb.-ft. torque at 1,300 r.p.m. It is used with a David Brown S.550 five-speed synchromesh gearbox, having Porsche synchronizers which give a fast, smooth and light change either up or down the ratios. The forward ratios are 7.81, 4.68, 2.76, 1.596 and 1 to I, reverse being 8.03 to I, and the gearbox is unit-mounted with the engine at four points.
A single-drive bogie, having an Eaton 18800 two-speed axle, with ratios of 5.14 and 7.02 to 1, is standard. Alternatively, a double-drive bogie with 7-in.-centre overheadworm axles can be fitted. Two ratios are offered-5.2 or 6.25 to 1. The two-speed axle gives a maximum road speed of 35.7 m.p.h., whilst the worm axles give top speeds of 35.4 and 29.4 m.p.h. respectively.
Semi-elliptic springs are used all round, with a balancebeam layout at the bogie. All the springs are 48 in. long and have 31-in.-wide leaves. A 21-in. 'diameter steering wheel operates the Marles cam-and-double-roller gear, and the track rod and drag link have self-adjusting ball-socket ends.
Girling Brakes: Eaton Axle
The front axle carries Girling HLS/S 16-in. by 3-in, twoleading shoe hydraulic brakes. The rear brakes are camoperated, and measure 151 in. by 7 in. when the two-speed axle is fitted, and 16 in. by 5 in. with the worm axles. A combined servo and air valve, similar to that employed on the 540 dumper, is fitted, the same safety features being applicable. The 560SF models with the Eaton axle have a total frictional area of 940 sq. in., whilst those with the worm axles have a total area of 664 sq. in.
Frames of the new models have 12-in.-deep side members, and fitted bolts are used throughout. A 40-gal. fuel tank is supplied and the 24-v. electrical system has a 288 W. dynamo and 81-amp.hr. battery. The standard tyres are 8.25-20 in. (14 ply), and a spare wheel and tyre are standard.
The new cab offered with these chassis is not unlike the KV6 cab employed on certain forward-control chassis. It does not extend the full width like the KV cab, the front wings projecting slightly beyond the sides of the superstructure. Much of the panelling is of plastics, based on a timber frame which has steel reinforcements. In common with normal E.R.F. practice, a large two-piece wrap-round windscreen is employed and the front grille is similar to that of the forward-control cabs.
There is a hinged bonnet ahead of the windscreen which is secured by two knurled screws and gives access to the radiator, air cleaner, heater, steering box and front cylinder head. The internal engine cowl is fully insulated against heat and noise. Standard equipment includes heater and demister, twin dual-drive electric windscreen wipers and chromium-plated bumper bar.
Gardner Engine: D.B. Gearbox
Specifications of the 66GSF chassis vary principally in respect of the engine, gearbox and axles. The power unit is the Gardner 6LW which gives 112 b.h.p. and 358 lb.-ft. torque. It is mounted as a unit with a David Brown 557/44 five-speed constant-mesh gearbox, the forward ratios of which are 7.92, 4.68, 2.74, 1.565 and 1 to 1, the reverse ratio being 7.92 to 1.
Because of the higher torque output the Eaton axle cannot be used behind the 6LW engine, so the standard bogie is a double-drive unit with overhead-worm axles which have 74-in. centres. There is a choice of axle ratios -5.6 or 6.25 to 1-and these give maximum speeds of 34.8 and 31.2 m.p.h. respectively. .A third differential can be fitted.
The 660SF has similar front brakes to the 56GSF, but the rear brakes are 161-in. by 6-in, units, giving a total frictional area of 824 sq. in. The standard tyres are 9.00-20 in. (14 ply), carried on B6 5-20-in. wheels.
A 56GSF 17-ft. 5-in-wheelbase chassis with Eaton axlc and 22-ft. body will be shown at Earls Court. Anothei exhibit will be a non-standard semi-forward-control tractor chassis based on the standard model, but powered by Gardner 6LX 150 b.h.p. oil engine and having a wheelbast of 12 ft. 31 in. This tractor is rated for a gross train weigh' of 40 tons and has a David Brown 557/480 10-speed gearbo) with overdrive top, and double-drive fully articulated bogie the 81-in.-centre worm axles having a ratio of 7.25 to 1.
A Westinghouse air-pressure system actuates the brake! on all wheels, and 11.00-20-in. (12 ply) tyres are fitted. Tht chassis has an overall length of 20 ft. and is 7 ft. 104 in wide. Both this and the 56GSF exhibits will be seen witl the new semi-forward-control cab.
The 18-ft.-wheelbase eight-wheeler exhibit is representa tive of certain changes that have been effected in all curren E.R.F. heavy-duty multi-wheelers. This model, the 68GX has the Gardner 6LX oil engine, parallel-depth chassi frame and eight-wheel air-operated brakes. The 6LX engini is now available as alternative equipment in all such chassis the other available power units being the Gardner 6LV■ 112 b.h.p. oil engine and the Rolls-Royce C4 133 b.h.p. oi engine. As used in the 68GX exhibit, the 6LX has a five speed constant-mesh direct-top gearbox, and a double-drivi rear bogie with 5.6-to-1 worm axles is installed.
Constant-depth Frame
The new chassis frame has side members with a constan depth of 12 in. throughout their length except at the front where the top flange is swept downwards to lower the cab floor height. Manufacture is simplified, wheelbase vani ations can be effected more easily and additional supper is given for tail-end loads when compared with the previou type of frame, in which the side-member section wa decreased over the rear bogie.
Eight-wheel brakes have been optional on E.R.F. eight wheelers for some years. Most chassis thus equipped hay been for export and have had air-pressure units, as oppose+ to the air-hydraulic system fitted to home models. Th latest layout has Girling two-leading shoe units on the fron axle or axles, actuated by a new type of compact air pressure cylinder. This bolts on to the standard backplat in place of the hydraulic cylinder, normally fitted an occupies little more space, so it does not affect front-whet lock. The rear brakes are operated by diaphragm cylinder in the normal way.
Other exhibits on the E.R.F. stand will include a 661 50-ton-gross tractor unit. This model, which was intro duced four years ago and has been selling well in Soutl Africa, is powered by a Rolls-Royce 200 b.h.p. six cylindered oil engine. A Rolls-Royce engine, the C4 NFI of 133 b.h.p., also powers the 48R 14-ft. 9-in.-wheelbas eight-wheeler which is to be shown by Edbro-B. and E This exhibit will have an 18-ft. body and, as with the 68GX eight-wheel air brakes are fitted. A third eight-wheele exhibit will be a 680 with a 24-ft. refrigerated container.
Detail developments common to all the new and curren E.R.F. models include the use of Micronic paper-elemen air filters, a high percentage of plastics panelling in th cabs, and paired headlights on some of the forward-contrc models. Purolator air filters are mounted inside the cal front panelling in the position formerly occupied by the oil bath units and access is given to them for element main tenance by a detachable interior panel.
Minor changes have been made in the interior layout o the standard cabs. They concern instrument and switc. position, trim and heating-demisting arrangements.