The LC4 Takes the Rough
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By Laurence J. Cotton, LLC By Laurence J. Cotton, LLC
M.I.R.T.E. with Ornooti WHEN first planning a day's work for the Morris-Commercial 25-30-cwt. lorry, I did not include off-the-road operation in the itinerary. Its appearance and build made me change my plans and the lorry was put through all the hazards on the Motor Industry Research Association's proving ground in the Midlands. I did not test it to destruction, but observed its behaviour on the washboard-surface and pave and over rough country, such as a model of this type might encounter overseas.
Shock absorbers, which are optional equipment on the home models and standard on those exported, were fitted to the test vehicle and, together with improved springing, made driving comfortable on the worst roads. The new full-width cab increases comfort, although the overhang of the seat over the enclosed step well makes dismounting a little difficult at first.
Other recent innovations in the 1.C4, as it is termed, include a centre bearing to the propeller shaft and low-pressure tyres. singles being employed all round. According to the recommended capacity, there is a slight overload on the single rear tyres, but most overseas operators would be willing to accept it rather than fit twin tyres, the inner pair of which might be grossly overloaded.
The four-cylindered overheadvalve engine developing 42 bhp. at 3,250 r.p.m. and 92 lb.-ft. torque at 1,500 r.p.m, gives a lively performance when the lorry is fully loaded and the torque curve is favourable to low-speed slogging across difficult sections of soft ground. The power unit is conventional, with a threebearing crankshaft and white-metallined shells for the main bearings. White-metal in the big-ends is run directly into the rods and caps.
The camshaft is chain-driven and operates the valves through pushrods and rockers, the rocker shaft and valves being removed with the cylinder head. Overseas models are equipped with an oil-bath air cleaner, but the vehicle tested had the normal baffle-type cleaner fitted to the domestic range.
A spring drive to the clutch centre plate obviates any tendency towards torsional oscillation in the trans
mission system, which now has a two-piece shaft with a centre bearing flexibly supported from a chassis cross-member. The four-speed constant-mesh gearbox is attached direct to the clutch housing and provision is made for a power take-off The wide radiator grille, 'blending wings and bonnet splaying out to the full width of the cab have improved the appearance and suggest powerful performance. With large low-pressure tyres, the LC4 appears to be well fitted to colonial conditions and these impressions were substantiated during my trials.
I noticed that the four-piece bonnet gave more than usual access to the power unit, and that there was ample space for heat dispersal. A built-in ventilation system is incorporated in the new cab, but the'poor conditions prevailing at the time of testing prevented any estimation being made of its efficiency.
Rain and heavy traffic in the Midlands would have made testing difficult on the normal route, so I elected to use the M.I.R.A track, which is within reasonable distance and safe under all conditions. I was greatly, impressed by the lorry during the journey to Lindley, especially when it climbed' Coleshill comfortably in second gear, and made a stop-start test on the 1-in-6 section with low gear engaged. The suspension and general driving characteristics made me decide to run token tests on all that the proving ground could offer in the way of cross-country conditions. This was my first encounter with the M.I.R.A. cross-country section, which combines a fair test of suspension and steering components, but lacks ditches or gradients.
The Morris-Commercial has highefficiency steering, and some effect is felt by the driver when the front wheels ride over projections, such as large pieces of brick, which abound on the course. I had a far better opportunity. later of judging steering. kick on the pave and washboard sections, Crew Comfort
The crew sit well within the wheelbase, thereby deriving greater benefit from the suspension. About 15-20 m.p.h. is a fair speed over the Lindley cross-country section and at this pace the lorry rode the bumps comfortably without pitching or harshness which might throw the crew out of the seat. Incidentally, the fullwidth seat provides sufficient room for three slim people, but three fairsized men in winter clothes might be rather cramped.
The pave and corrugated sections' are popular for testing all makes of chassis and three or four different types of vehicle can usually be seen bouncing along in convoy. Because of the heavy rain, the cavities were filled with water and as we drove along the pave at speed, the tyres flung out spray for 10-12 ft. Again I awarded full marks to the vehicle for its smooth riding. It performed well also on the washboard section, where it kept a straight path with little movement of the steering. Between these two sections, the rain had become trapped in a miniature water trough approximately 4-6 ins, deep, and I could not resist driving through it at a moderate speed. It was rather deeper than I thought and meeting the worst part at 20 m.p.h., the entire front of the vehicle was enveloped in spray. Apart from its. retarding force, the water did no harm. The engine continued to fire evenly and the brakes worked without pulling or apparent loss of efficiency.
54 ft. from 30 m.p.h.
During the succeeding tests, an average stopping distance of 54 ft. from 30 m.p.h. was recorded, all four wheels locking for practically the whole stretch. There was less wheel locking at 20 m.p.h. „and the retarding force of 0.7 g., equal to a stopping distance of 19 ft., is perhaps a more reasonable estimate of the optimum braking effort.
There is no speed limit on the Lindley track, but the distance available restricts the speeds which commercial vehicles can reach. I was able to make two testa from standstill to 45 m.p.h. in each direction, and it was apparent from the results that the Morris-Commercial did not lack liveliness. To accelerate from 0-40 m.p.h. in less than 40 secs, is a reasonable performance.
Tests on the proving ground are devoid of involuntary stops, but apart from this, the fuel-consumption rate should closely approximate to that expected in normal_ road operation; because there is a corner to be negotiated at every mile. In 12 miles continuous running, 4.8 pts. of fuel were used, which works out to 20 m.p.g., and as the trials occupied 234 thins., the average speed corresponded to 30.6 rn.p.h. Making one stop per mile, which is akin to local . lorry operation, the consumption rate worked out to 16 m.p.g.—a reasonable figure.
A vehicle of this type, which might be employed in the narrow confines of a market or builder's yard, needs
to be manceuvrable. It requires a short wheelbase, which in the case of the Morris-Commercial is 9 ft. 6 ins., and a good steering lock. The measured turning circle of 43 ft. compares well with that of many retaildelivery vehicles.
During my spell at the wheel on the way back to Birmingham, I indulged in some fast driving and high-speed cornering. The LC4 likes a burst of speed and is willing to keep it up wherever conditions permit. Low-pressure tyres give good adhesion when cornering fast and it is only when exceptional liberties are
taken that the tail tends to wander. I was satisfied with the vehicle in all its trials and feel confident it will be a specially popular model with overseas operators. The smart appearance of the vehicle, which is goad publicity to any operator, is combined with crew comfort and good road or roughcountry performance.