The McCurd Five-ton Chassis.
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A Well-known Machine Improved in Detail, and with its Capacity Increased so as to Accommodate a Gross Load of Five Tons.
Our first published description of the McCurd cha.s&is was presented to our readers so far back as November, 1912. At that time the whole of the business of manufacturing these chassis was conducted at the Store Street premises, Tottenham Court Road. Such, however, has been its success that it has been found necessary to open new and enlarged premises in order successfully to meet the demand. On a recent occasion we took the opportunity to call round at Edgware Road, Cricklewood, where we fouled Mr. McCurd and his workpeople firmly established in the beautifully-located works covering some two acres of ground, and discovered it to be, in many respects, a model of organization, and to have the capacity and equipment to enable the company to manufacture itself most of the essential portions of the chassis, the exception to this rule being items which ale specialized, sueti as, for example, the engine crankshaft.
Freedom from Small Mishaps.
From the very nature of things a feature of the McCurd chassis, as a whole, is bound to be its freedom from minor worries following the lack of a proper amount of attention on the part of the driver. As we . pointed out in the original article referred to above, the design has been dictated to a very considerable extent by the results of Mr. W. A. McCurd's long and varied experience of repair work, which he has superintended, and in the course of which he has dealt with many various types of chassis, both touring and commercial. That Mr. McCurd was justified in the main has been proved during the course of the last three years by results in the hands of various users of all kinds. We may state that, following on this experience, it has not been found necessary to alter to any extent the original design, so far as the principal portions of the chassis are concerned. Such additions and changes as those we are about. to record are similar to others which are found necessary in every new model as the result of the early days of its commercial utilization. They consist of minor alterations to details. We may .remind our readers in this connection that our expressed opinion of the chassis in the course of the " first description" was favourable ; cir conception of its probable value to users is amply borne. out by the results of their experiences under numerous severe classes of use.
Two Individual Instances cf Good Service.
We were fortunate in being able to inspect at the time of our visit a couple of these hard-worked machines. One has been in the service of the Essex County Council Roads Repair Department for many months past. It carries a metal body, the weight of which we were informed is well over a ton, and has frequently been loaded to such an extent that, in order to withdraw it from its position in soft roads it has been necessary to use another machine to tow it. The chassis was recently returned to the makers, and Mr. McCurd was given practically a free hand with regard
to repairs. As a result, from .a careful overhaul and examination of all the parts liable to wear, the total amount of repairs necessary to a, machine which, let it be remembered, has been constantly overloaded and much overworked during a lengthy period, amounted only to 220. Another vehicle, in much the same condition as regards need for repairs, had done 16,000 miles in the course of twelve months running.
Thorough System of Lubrication for Engine.
The specification of the chassis embodies a power unit of four cylinders, 4?.; ins. by 51 ins, bore and stroke, the outstanding feature of this being its lubrication system, which includes a plunger-type pump situated at the bottom of the crankcase sump, and
so arranged that it can be removed instantly for inspection and afterwards returned with ease. The crankcase lower half is of such a capacity that it will hold f34gallons of lubricating oil. Our readers may also remember the unique method adopted for cooling the lubricating oil. Holes are cast in the bottom half of the crankcase, and in these steel pipes are fitted, the arrangement allowing of the sontinual passage of cold air through these pipes, round which, of course, the oil circulates. The depth-indicator is of the float type, and embodies a piece of in. tubing as the visible indication of lubricant available, instead of the usual wire pointer. Another point of note in regard to the engine is the very large size flywheel which . is incorporated, this serving as the . outer portion of the leather-lined cone clutch.
Unique McCurd Gate-change.
The transmission incorporates a four-speed-and-reverse gearbox, , and in connection with this unit. it should be noted that the unique form of inverted change speed gate is still a feature cif the chassis. The gearbox itself is very compact with short shafts. No . keys are used, all the wheels being driven on to splined shafts. A point tAt strikes one when surveying the chassis is the apparently enormous size of the universal :joints it the ends of the propeller shaft. We say apparently, because, although the joints themselves are perhaps a little larger than usual, the bulk which appears so prominent on first inspection is in a great measure due to the fact that these joints are enclosed in large aluminium oilcarrying eases, the object being to provide such a cariacity foi lubricant that, once full, the joints will not need further attention for a considerable period. A special form of thrower-ring is incorporated in the design of the covers, so that the oil contained has very little chance of escaping. As a further safeguard, leather covers are attached to the outsides.
It is in regard to such particular features as this that such experience as has fallen to the lot of Mr. McCurd is so valuable. It is generally agreed that. universal joints are frequently a• source of trouble.
Special Position for Torque Rod,
A special feature, and one which may be described as an innovation since our previous description of the chassis, is the torque rod. As our illustration shows, this, instead of being, as is more usual, attached to the front half of the axle casing and anchored at its front end to a. cross-member very close behind the gearbox, is fastened by means of a special universal joint to the top of the worm-gear easing, and attached at its other end to the rear crossmember of the frame. Mr. McCurd claims that by this unique construction he avoids to some extent the jolting consequent on a sudden application of the clutch. The torque rodi:!itself is of such a length that variations in the relative heights of tins chassis and axle assist in fixing the centre line of the worm in its correct relation to the axes of the remainder of the transmission.
Efficient braking is afforded by the customary foot and hand brakes. One of our illustrations shows the very positive and distinct form of external shoe For the side brake. The foot brake, which takes effect on the large drum behind the gearbox, is similar in respect of its capacity for hard work. Means of radially adjusting both sets of shoes for wet are provided. These are both accessible, and the operation of taking up can be effected without the aid of a spanner.
• Steering Gear.
Further evidence, of careful design and attention to detail is noted on consideration of the steering gear. The worm and sector are contained in the usual type of cast box, the worm being carried between thrust bearings. The sector is provided with unusually long hearing surfaces. It is carried by a phosphor-bronze bush, the bore of which is eccentric with its out
side diameter. The outer end of this bush has a flange with holes drilled at intervals.. By rotating this bush, of course, the centre of the, sector is moved to or from the centre of the worm in case of need. It will be realized that, by the aid of this ingenious fitting, it is possible in the 6rst place to insure extremely accurate setting of worm and wheel, so that they are in perfectly correct mesh, and alSo it is possible, as time .goes on and wear becomes evident, to close in these centres somewhat to take up any
play. t should be pointed out in addition that both worm and sector are made of Special case-hardened steel, and that, as a consequence, a lengthy period should, elapse, before thiS need for adjustment becomes evident.
Accessibility. The Radiator.
The feature of accessibility has certainly not been lost sight of. The engine and gearbox are both threepoint suspended, the same means
• having been adopted for each. The front portion is carried by a special cast-steel bracket, and either of these units can be very quickly re. moved after unfastening three bolts. The clutch and clutch inc. chanism are also similarly arranged for easy access. The McCurd radiator byl•-now is thoroughly well • known and needs no description. The steering lock, which has been a feature of this chassis from the commencement, has been retained, notwithsLinding the fact that. owmg to difficulty in obtaining forgings, the Butler type of front axle is at present being used. The 'feature to which we referred in the previous description, in that it was provided with a third brake for special emergencies, has not been continued. The provision for the fitting of this, however, has been
made, and the details can be fitted if they are at. any time desired.
The frame construction is somewhat unusual in that rivets are not used, the whole being bolted together. It is interesting to note that this portion of the chassis also is built on the premises at Edgware Road.
We think that the McCurd Lorry Manufacturing Co., Ltd., of Edgware Road, Cricklewood, is to be complimented on having successfully produced such a chassis, and that users also should be congratulated on having at their disposal another sound example of all-British production.