New 150 b.h.p.
Page 68
Page 69
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Engine from Gardner
AMAXIMUM power output of 150 b.h.p. at 1,700 r.p.m. is the rating of the new Gardner 6LX six-cylindered direct-injection oil engine, full details of which were announced this week. The unit has a cubic capacity of 10.45 litres (638 Cu. in.) and bore and stroke of 120.6 mm. (4.75 in.) and 152.4 mm. (6. in.) respectively.
It has the same box dimensions as the well-known 6LW unit and is interchangeable in respect of engine mountings, flywheel housing and so forth. Excluding electrical equipment it weighs approximately 1,583 lb. The maximum torque output of 485 lb.-ft. is developed between 1,000 r.p.m. and 1,100 r.p.m.
Following normal Gardner practice, the new engine has separate cylinder block and crankcase, and, as with the LW range, the crankshaft is unhardened. Provision is made for mounting a Gardner exhauster or proprietary makes of air compressor, whilst there is a flange for carrying a hydraulic pump for power steering.
The crankcase is an aluminium-alloy casting designed to be light but extremely rigid. It has generous ribs inside and outside, which, together with its deep vertical section, ensure. adequate support for each crankshaft main bearing.
The main-bearing caps are cast in hightensile aluminium alloy and fitted with girder-section forged-steel bridges, which spread the support from the throughbolts. The front end of the crankcase contains the timing drive.
A special ductile high-tensile iron is employed for the one-piece cylinder-block casting, which carries dry-type liners. Large-diameter cylinder-head studs are fitted close to the cylinder bores to eliminate gasket troubles, and water passes from the cylinder into the head via small spigot tubes with synthetic-rubber joint rings, so that the steel-and-asbestos gasket is not called upon to make a water joint.
The block is attached to the crankcase by means of high-tensile through-bolts. which extend through the crankcase and form the main-bearing-cap studs at their lower ends. This construction is claimed to permit the use of an aluminium crankcase and at the same time provide greater c28 rigidity than is possible with cast-iron, whilst saving some 300 lb. in weight.
Cast in high-tensile iron, the two cylinder heads have hard alloy-iron inserts for the valve seats. Single exhaust and inlet valves are carried in the heads, and the valves and push-rod ball ends are lubricated from the hollow case-hardened valve-rocker shaft via passages drilled in the case-hardened rockers. The oil flow is regulated, so that excess oil does not reach the valve ends. The inlet valves are slightly larger than the exhaust valves and masked. These masks, in conjunction with the carefully controlled shape of the inlet passages. produce the correct degree and direction of turbulence within the cylinders. Duplex valve springs are employed and the valves work in renewable guides.
The crankshaft is a high-tensile-steel die-stamping machined all over, and neither locally nor surface-hardened. It has large-diameter hollow main journals and crankpins, and runs in seven whitemetal-lined bearings with bronze shells, and one roller bearing at the forward end. The front of the crankshaft carries the triplex-chain sprocket for the timing and auxiliary drives and a twin-V pulley for the fan drive. A friction-type torsional vibration damper is fitted within the crankcase.
Lubrication of the crankpins is through steel tubes pressed into hollows drilled across the shaft from journal to pin, thus eliminating sludge pockets.
The connecting rods also are diestampings, using high-tensile alloy steel. The big-ends are of the two-bolt type and the rods are rifle-drilled from end to end to provide a central duct for forced lubrication of the little-end bearing. Thin-wall steel shells, lined with specially surfaced copper-lead, are used for the big-end bearings, whilst the little ends are bronze bushes pressed into the rods.
Medium silicone aluminium alloy pistons of patented Gardner design are employed. A hemispherical combustion chamber is formed in the top of each piston and two compression rings and one oil control ring are fitted. A diameter hollow gudgeon pin is retained laterally by means of aluminium pads.
The camshaft assembly is carried in seven white-metal-lined bearings, with a roller bearing in the timing cover. The inlet and exhaust cams are made in pairs and fixed to the camshaft by means of special 60 pointed setscrews, this arrangement simplifying cam regrinding.
The lubricating-oil pump is carried in the lower. part of the crankcase, where it is driven from the valve camshaft through helical gears. A gear-type pump is employed. Where engines are required , to operate at extreme angles to the hori
zontal, the oil pump can be arranged to embody a secondary pump to return oil from the low end of the sump. The sump itself is an extensivelyfinned magnesiumalloy casting with a metal-to-metal joint to the crankcase.
A C.A.V. BPF fuel-injection pump is operated by Gardner cams and tappets, as is the normal Gardner practice. The C.A.V. blocks of pumps arc mounted as a pair, whilst the pump camshaft is supported on large ball bearings and driven through a helical gear which meshes with a similiar gear on the valve camshaft.
This gear is free to slide on a helical spline on the• pump camshaft and by means of a yoke coupled to the accelerator lever the gear can be moved axially, thus varying the timing with engine speed. The lubrication is supplied from the main fuel pump and an all-speed mechanical governor is used. Two paperelement fuel filters are provided.
Multi-hole fuel sprayers are employed and each is retained in its cylinder head by one stud and a clamp lever. The sprayer nozzle cap makes a metal-tometal gas-tight joint on a conical seat at the bottom of the sprayer hole in the head. Small-bore steel injector pipes are used.
The water-pump body is cast from a special corrosion-resistant aluminium alloy and has a spherical carbon gland working in conjunction with a self aligning ball race. . .
A C.A.V. 24-v. axial-drive starter is fitted unless otherwise specified.