A series of articles by the Chief Bodywork Designer for Morris Commercial Cars Ltd, T. Evans, appeared in Morris Commercial publications in the mid-1930’s. As some of the information contained therein is of particular interest to members restoring commercial vehicles, extracts are reproduced here.
In the selection of suitable materials for body construction the weight factor plays a highly important part, for whilst certain extremely light alloys cannot always be employed by reason of their comparatively high cost, much can be and is being achieved by a careful study of the more orthodox materials.
Metal construction has – during recent years – made a marked advance, but for commercial bodywork, timber is still the main raw material, and for all classes of framework colonial, and American ash is used extensively, being strong, durable and considerably lighter than either English ash or oak. Now whilst these timbers have a higher strength factor of value in such applications as heavy vehicle bottom frames, the colonial ash has certainly proved its efficiency for a very high percentage of general framing members. Canadian yellow birch is also used to a large extent in this country and compares very favourably with ash but is slightly heavier. Red beech is also sometimes used for the lesser items of framework and compared with ash is about equal in weight, although certainly not as durable.
Most Suitable Timber
All factors considered, therefore, a good quality colonial ash is the most suitable timber in this connection particularly where the total weight has to be maintained at a minimum. Many of the lesser known timbers of both empire and foreign origin have been tried, and whilst certain of them compare very favourably with ash, only one in the writer’s experience, namely ‘serayah,’ shows any appreciable saving in weight and is, therefore, a very useful material for, say, bulk capacity or pan-technicon framework, where this question is of vital importance (origin – Borneo and the Malay peninsula).
Softwoods are used principally for floors, roofing and truck sides, deal, spruce and British Columbian pine being the three most useful timbers in these applications. Silver spruce is the lightest and may be used successfully for truck sides, roofing, bearded partitions and interior fixtures generally. It is not, however, quite as strong as red deal or B.C. pine, these materials being, therefore, more suitable for truck or van floors.
PICTURE: Modern treatment of the fronts of bulk capacity bodies greatly enhances the general appearance.
The exterior panelling of van bodies also contributes considerably to the total weight, particularly on large three- or four-ton bulk capacity vans where some 250 so. ft. are required. At the present day, however, we have a number of excellent materials from which to choose, thanks to the progress made by various firms specialising in their manufacture, and the following list shows at a glance the weight saving that can be affected in this section of construction even though a little extra cost is entailed:-
|lb. per sq. ft|
|Silver finished steel sheets||20 s.w.g||1.47|
|Aluminium sheets||16 s.w.g||0.9|
|Aluminium sheets||18 s.w.g||0.875|
|Single faced steel amour ply||1/8 in.||1.16|
|Single faced steel amour ply||3/16 in.||1.39|
|Single faced aluminium amour ply||1/8 in.||0.7|
|Sundeala board||3/8 in.||1.25|
|Masonite board||3/16 in.||1.062|
Turning to the various metals employed, steel is still used in most cases for all kinds of fittings and reinforcements for, as previously mentioned, certain very excellent light alloys have a cost disadvantage sufficient to retard their adoption generally. Their value in certain specific applications is, however, easily appreciated when one considers that a metal such as duralumin is equal in strength to steel and only one-third the weight. Aluminium of varying grades is also used extensively for mouldings and various fittings – again in the interests of weight reduction.
The bottom frame of most bodies is usually the heaviest section, particularly on truck type bodies having a flat platform, for here the depth of the runners and cross bars is governed to a certain extent by the requisite clearance over the rear road wheels, and not entirely by their sectional strength requirements.
Much can be achieved, however, but careful distribution of the cross members in proportion to the body length, and a definite saving is also registered by designing the intermediate members as parallel edged members fitted with making up pieces at each side where they rest upon the longitudinals, instead of cutting them out of a deep solid bar.
PICTURE: Demonstrating the relationship between immediate pillars, crossbars, and roof sticks in the construction of van framing.
The longitudinal runners may be lightened by cutting down their depth a little between cross members as they are supported through practically the whole of their length by the chassis frame, but any overhanging portion at the rear may, of course, be maintained at the full section.
The bottom framework of van bodies is a much simpler problem from a weight aspect as wheel arches are usually permitted in their design, and the longitudinal members may, therefore, be dispensed with, support for the rear of the body being obtained by the extension of the chassis frame side members.
As regards what may be termed the upper structure of van type bodies, which include the side, front and roof framing, efficient distribution of framing members is highly important to attain strength coupled with lightness. Thus better results are frequently obtained by keeping the intermediate pillars, rails and roof sticks light in section but spaced at reasonable intervals than by fitting an inadequate number of heavier section members. This latter principle results in no saving in weight as compared with the former and provides less support than necessary for the side panels and roof covering.
Correct Jointing Methods
Light framing also compels the adoption of correct jointing methods for, as previously pointed out, the ultimate resistance of most members to any individual stress is governed by their sectional strength at the points where they are jointed to other members. For this reason it is customary to proportion the vertical pillars of van bodies considerably more in width than thickness. The laps may then be safely cut on the outer face to receive the various longitudinal rails that must pass across them.
This also permits the rails to be maintained at a minimum section, for no more than is necessary to provide a location need be cut out at their joints, as the major portion of the lap is taken out of the pillar.
In the construction of all types of doors, weight should be cut down wherever possible for, in addition to the general interest, a heavy door imposes such work as will necessitate stronger, and therefore heavier, hinges, locks and dovetails. The various framework members should, therefore, be lightened out where possible, implying that in many instances a certain section of bottom rail is necessary to ensure a strong lapped joint on to the pillars but nevertheless allowing a reduction to be made between the joints without in any way impairing the strength of the completed assembly.
Large van rear doors call for a strong framework securely jointed to prevent a natural tendency to whip or twist but rather than increase the section of the members excessively, it is a better practice to line the door on the inside with a light plywood securely fastened to the framework. The additional stiffness obtained by this method results not only in a light structure but also in an exceedingly strong one.
PICTURE: Detail parts of a forward-control cab side assembly showing the amount of accurate machining required.
Truck sides and tailboards should be strongly hinged to the lower framework, and also be quickly and easily detachable, as certain loads necessitate their complete removal. In this connection, whilst it may be good design to fit rigid and permanent centre and rear corner posts on long heavy vehicle bodies, they should not be included on the lighter or even medium capacity trucks, in view of the obstruction they present when the vehicle is being operated in this manner.
The sides on most modern truck bodies are of sufficient depth to allow an interior height of approximately 18 in. and they are usually reinforced to take the stress of bulging loads in proportion to their length. Strict attention is also paid to the fitting of protection plates to the edges, also to the top edge of the chock rails, and at intervals across the platform, as these add considerably to the life of the parts concerned.
Touching on the general design and construction of tipping bodies, we again find a very marked advance, particularly in respect of the actual tipping gear. On the hand-operated type we now have the screw universally mounted, allowing self alignment should the body be tipped with the vehicle standing on uneven ground. In addition, the latest designs of power-operated gears have so proved their efficiency as definitely to justify the extra capital outlay involved, particularly on vehicles of over two tons capacity.
Under the heading of van bodies we have an even greater variety of types than in the case of the trucks, but, in a like manner, we find on examination distinct essentials that form the basis on which most van type bodies are designed. First again in order of importance is the question of load space, and in this instance we are concerned more with cubic capacity than with actual platform area. Further, these three governing interior dimensions – length, width, and height – have a very important bearing on the general balance and finished appearance of the completed body. We are also faced with the fact that the height of the load is in many cases equal or greater than the width, thus affecting the general stability of the vehicle.
PICTURE: Rear overhang of the bottom framework of a van body showing the straight-through longitudinal members.
Another item calling for keen attention is the general accessibility affecting loading and unloading. The almost universal method adopted today is through the rear of the van, side arrangements being principally used as extra means of access on large or special type bodies. The rear doorway should conform as nearly as possible to the interior dimensions of the body. This is most essential for example on bakers’ and confectioners’ vehicles.
Full height double doors are now fitted to a high percentage of vans of all types to ensure complete protection of the goods carried. The spring roller shutter has also proved its popularity in this connection, being exceptionally quick and easy to operate – the only drawback to this method being the additional height required to house the shutter above the rear aperture when open, but where, as in most cases, bodies are not loaded to their extreme interior height, this factor remains of little consequence.
Having covered, to some extent, the practical requirements of commercial bodywork, we can now consider general lines and finished appearance which, as previously noted, have improved beyond all measure during recent times. This feature is perhaps most apparent to us on the smaller vehicles, and can doubtless be attributed to their general proportions being more adaptable in this respect.
With the larger bodies, however, one also notices a very marked improvement. Let us take, for example, the present day treatment of the front portion of bulk capacity and pantechnicon type bodies. A generous slope is given to the windscreen and front panel of the compartment above the driver’s cab – this line, terminating in a well proportioned radius over the roof corner, and coupled with similar radiused panels on each of the side corners, results in a very pleasing and smart appearance. Incidentally, this manner of treatment to the fronts of large bodies reduces the air resistance set up by large frontal surfaces, with obviously beneficial operating results.
The separate driver’s cab used in conjunction with all manner of truck bodies provides another striking example of the better finish and general appearance that is now achieved. In fact, this particular item is subjected to practically the same treatment today as the private car, as we have a true streamline to the scuttle and cab sides, a sloping windscreen and domed roof and rear corners.
Assembling the Framework
Special jigs are used to ensure accuracy and correct fitting together of the various joints.
In order to appreciate fully the efficiency attained by this method of constructing body framework, let us visualise, for example, the type of jig used for a light van side assembly. This section is usually built with a front vertical pillar, three intermediate and one rear pillar, four longitudinal rails consisting of one lower skirt rail, two waist or moulding rails, and one top or- to use the correct term – cant rail. There is also the longitudinal bottom side-which is the member that connects up with the floor of the body, and also the bent wood rail known as the wheel-arch bend.
The jig used to ensure correct jointing together of these parts into one complete van side framework is built up on a trestle-like structure at a height convenient for the workmen, and is fitted with location blocks which maintain the positions of the parts mentioned in correct relation to each other.
Various forms of clamping devices are fitted where necessary to grip the joints firmly together before they are secured by the screws or bolts, whichever may be the case. These methods of assembly, as one can appreciate, ensure that all body units will be perfectly true and accurate, factors having an important bearing on the final assembly, as incorrect lining up of the framework in the initial stages would result in harmful pent-up stresses at various points of the body when completely assembled.
The principle of standardising various constructional parts and fittings on different models also facilitates maintenance, particularly for large fleet owners whose vehicles are equipped with various types of bodies. In this connection, for example, the driver’s compartment door is today identical on all Morris-Commercial normal control vans and trucks from 15 cwt. up to 3% tons capacity. (Morris Commercial C-type).
This arrangement is of great assistance in servicing such parts as drop window mechanisms, locks and buffers. The same principle is carried out, if not quite to the same extent, on such items as windscreens, cushions and a considerable number of smaller body components.
Constructing Body Framework
The sides and tailboards of most truck bodies of a capacity up to and including 3 tons, are constructed of a number of tongued and grooved boards held together by vertical hardwood battens on the inner face, and by the hinge irons on the outer face. In deciding on the number of boards to use for making up a complete side or tailboard, the possibility of shrinkage should be considered as joints that have opened are weak and impair the general appearance.
Whilst it is not possible completely to control shrinkage, a little forethought will minimise the effects produced. For example, a 15 in. side made up of four 3314 in, boards will be more satisfactory in this respect than three 5 in. boards, the reason being perfectly clear on considering for a moment why timber alters under varying conditions.
Effects of Moisture
First, the moisture content of most exposed timber structures is governed largely by the existing atmospheric conditions. In warm, dry weather, therefore, moisture is dried out and shrinkage of the boards takes place. As shrinkage is a function of the width of a board it will be appreciated that a reduction in the width of a board correspondingly reduces its absolute shrinkage and, therefore, an assembly constructed of narrow boards will show at each joint a smaller shrinkage gap than a similar assembly consisting of wider boards. In either case the total shrinkage would be the same, but narrower boards, necessitating a greater number of gaps, show a proportionately smaller gap at each joint.
The hinges fitted to both sides and tailboards are perhaps the most important items of truck ironwork as, apart from hinging the sections referred to, they also act as a reinforcement and, in view of this, the section of the material used should receive due consideration. Most of the stress on these hinges is applied at right angles to their face and if, as is commonly found, flat section steel is selected for the manufacture of these parts the thickness must be-from the writer’s experience it should not be less than 3/8 in. – as to afford adequate strength.
On sides over 9 ft. in length we find some extra reinforcement necessary if effective resistance is to be offered to loads of a bulging nature. This can be obtained by fitting a mild steel angle – or preferably channel section – along the top edge, or by securing a timber rail in the same position having a wide convex section steel top capping.
The majority of van bodies today have arches constructed over the rear road wheels, thus permitting the lowest load line possible to be obtained consistent with suitable bottom frame construction. A series of cross members spaced at intervals from front to rear contribute the major portion of the support, and they must therefore, have a correct sectional strength, in accordance with the load capacity of the particular body in question, plus a safety factor ensuring efficient resistance to the additional forces. On the other hand, however, their depth should certainly not be more than conditions demand or the load line will, of course, suffer accordingly, apart from the weight factor which must at all times be taken into full account and kept as low as possible.
This question of providing sufficient strength at a minimum of sectional depth calls for extreme care in the methods adopted for jointing the various framework parts; otherwise a large proportion of the intended strength is wasted. In this connection no better example can be taken than an instance of where the body overhangs the chassis frame to a considerable extent at the rear. Here, it will be appreciated, substantial longitudinal members must be included in the bottom framework, arranged to register and to take their support from the chassis frame side members, but extended beyond them to carry the rear of the body.
Under such conditions we find these members are stressed to an even greater extent than those arranged transversely – particularly where they leave the end of the chassis frame. While on many chassis, frame design permits metal extensions to be secured in such a manner as to provide adequate support , others are not so adaptable in this respect.
PICTURE: A van side assembly jig showing a completed side framework lifted out.
With a construction of this type cross members cannot be placed on top of the longitudinals as this course would make it impossible to obtain a low floor level. They must therefore be jointed across or into each other in such a manner that little or no increase in the overall height of the frame results.
In this application the practice known as ‘half lapping’ is successfully used, providing the strength of each member at the points where the laps are cut is adequate. This cannot always be obtained; for instance, should a cross member be required to register with the end of the chassis frame, a joint of this description would weaken the longitudinal member by half at the exact point at which the maximum stress occurs.
Rear Frame Treatment
Excellent results can be and are achieved in such instances by the application of suitable metal reinforcement ensuring the required distribution of the load imposed.
Even better results can be obtained by individual attention, and the sketch here shows the Morris- Commercial method. Here, it will be noticed, the body cross member falls over the rear cross member of the chassis frame, and it is, therefore, possible to split this member into three sections by taking advantage of the support by such a useful relationship of members. This permits the longitudinals to pass through the cross member and retain their full sectional strength throughout with only a light metal reinforcement as a safety factor.
The two outer sections of the cross member are, it will be noticed, bolted to the overhanging part of the chassis member, and as the centre is mainly giving support to the floorboards passing over it, this is secured by mild steel plates strapped across the joints.
The reinforcement of timber members with mild steel plates is usually employed in cases where additional strength is necessary without increased dimensions. The longitudinal members are a striking example of this, and from the writer’s experience, a mild steel angle section correctly applied will give a far higher strength factor than the usual flat section one often sees secured to one face of the member. This is easily appreciated for, in the case of the angle section method. any over-stress taken on the member is immediately transferred directly to the reinforcement as it is actually seated on one side of the angle, whereas with the flat section bolted on the one face only, at right angles to the direction of stress, reinforcement is obtained only from the bolts or screws securing the plate to the actual member and, therefore, the sectional strength of the plate used is not fully employed.
Side and Roof Framework
With the general delivery type of van body the side framework is mainly constructed of vertical pillars and longitudinal rails, the number of intermediate pillars and rails being largely governed by the length and height of the complete framework and also by the type of panelling used. From the strength aspect, however, which is the prominent feature of these considerations, the vertical pillars should, wherever possible, be jointed to the bottom frame side members at points adjoining the cross members. They can then be secured with bolts and reinforced with light steel plates – one leg being bolted to the pillar and the other to the cross member. This same procedure should also be repeated when positioning the transverse members, or roof sticks, of the roof-framing, thereby completing a series of cross sectional frames throughout the body.
It is easy to see the advantages of this system of setting out van body framework. Apart from providing maximum resistance to the various stresses, the system ensures a correct distribution of the work in the respect that each member is receiving support from the adjoining members.
The method of construction usually adopted on the tilt van type is also particularly successful in this direction, as here one complete timber rail is bent to form pillars and roof stick. Returning to considerations of side framework, we generally find the vertical pillars are greater in their sectional depth than the longitudinal rails. This is essential to ensure adequate strength remaining after the lap joints have been cut for the rails. Providing both parts are suitably proportioned for their particular purpose and present a flush finish on the outer face to receive the panelling, any further levelling up results in unnecessary weight.
The method of constructing the rear of a van body is governed – perhaps more than any other section – by the type of work for which it is required. On most delivery vans, rounded rear corner panels may be incorporate without having any ill effect on the loading facilities, whilst they add considerably to the finished appearance. The framing necessary in the construction is entirely suited to the work imposed, and the actual metal panel provides additional stiffness. Where the type of load demands a rear aperture equal to the interior width of the body – as is required by the bakery and confectionery trade – a corner pillar is more suitable. When service conditions call for rear doors hung on outrigger hinges, enabling them when open to lie flush against the body sides, the rounded metal corner is not so suitable for the mounting of this particular design of hinge.
Many vans, such as the luton and laundry types, which usually have an interior height of 6 ft. or more, are only fitted with a drop tailboard and curtains. Here wider section corner pillars may be fitted, resulting in the exceedingly strong construction that is so necessary. With all forms of rear framework, however, it is of common importance that strong, reinforced joints are obtainable at both the lower and upper corners, for here the greatest stresses occur in this particular section of construction.
End Tipping Truck Bodies
The weight of the load to be carried, its nature, and the manner in which it must be handled, are the chief factors to be borne in mind in the design and construction of commercial vehicle bodies generally. In the case of tipping bodies the last mentioned factor affects the whole of the construction and the means of attachment of body to chassis as tipping lorries are designed for the express purpose of handling materials that cannot be economically unloaded in the orthodox manner.
In the preliminary layout of any type of tipping body, strict attention must be given to the question of suitable capacity and general proportions to ensure an equal load distribution on the chassis, both when travelling and also when the body is being lifted for purpose of discharging the load.
Short wheelbase chassis are mainly used as a basis, permitting an interior body length between 8 ft. or 9 ft., and varying from 5 ft. 6 in. to 6 ft. 6 in. in width. These dimensions can be taken as covering vehicles from, say, 30 cwt. up to 4 tons carrying capacity, the height of the sides being usually greater in the latter case.
Assuming that suitable interior dimensions have been decided upon in relation to the chassis and load capacity, the next important step, to ensure correct proportions, is the fixing of the location for the rear pivot or hinge centre, which should in all cases be positioned as close to the rear axle as possible. If this is aimed at it will be found that the nearest point is slightly forward of or directly over the back spring rear bracket.
By pivoting the body about this point load distribution will be correct not only when the vehicle is travelling but also when the load is being tipped,as it will be easily appreciated that the forward placing of the pivot considerably reduces the load on the lifting gear. Further, and of equal importance, the stress imposed upon the chassis frame when the body is being tipped is taken at a strongly supported section, and not on the extreme ends of the frame side members.
From the writer’s experience the correct location of the pivot usually gives a proportion of two-thirds of the body length forward of the pivotal point and one-third rear overhang.
Bottom Frame Construction
Strong, soundly constructed bottom framework is essential to the success of all classes of bodywork but with tipping bodies it is of exceptional importance as during tipping operations little or no support is obtained from the chassis frame. The longitudinal bearers or runners must, therefore, be of sufficient sectional strength to support the load distributed over their length, better distribution being achieved by spacing the intermediate cross members more closely than on the ordinary truck body.
While considering the necessity of bottom framework strength on this type of body it is opportune to draw attention to correct methods of securing the tipping gear and rear hinges to the body. The rear hinges on most bodies today consist of two brackets at each side, one being seated upon and bolted to the top chassis frame side member flange, and the other secured to the side face of the body runner, a mild steel bar of not less than 1½ in. diameter passing through both sets of brackets. In some cases body brackets take their load only through their securing bolts. This, it will be appreciated, is not sound practice and conditions are greatly improved if small lugs be included in the bracket design providing a definite seating for the bottom face of the runners and relieving the securing bolts of direct shearing stresses.
PICTURE: Showing how weight may be saved in truck bottom framing.
Lifting Bracket Support
With either the hydraulic ram or hand screw type of tipping gear situated between the rear of the cab and the front of the body the method of securing the actual lifting bracket is governed by the same important strength factors. It is not sufficient for this bracket to be merely bolted to the front cross member or boards – as is sometimes seen – but it should be designed with a flange at least or fitted with additional steel plates that will pass under the bottom face of the front bar. If this is done the securing bolts are again relieved of considerable shear stress. Further, no undue stress is transferred to the front boards of the truck.
On bodies designed for 3-ton loads or more, this distribution of work should be carried still further, as in the case of the Morris-Commercial 4-ton tipping model. Here the ram body bracket, by reason of a specially designed reinforcement, virtually exerts ifs lift under the front ends of the longitudinal members. This is achieved by fitting a mild steel angle section support to the bottom edge of the front cross member, which is set down at each end, and under the bottom face of the runners, the bolts securing these members to the front crossbar passing through the horizontal flange of the angle. The ram bracket, being designed with a flange at right angles to its vertical face, is, therefore, when secured in position applying the lift to the angle support which, as described, distributes it to points each side under the ends of the longitudinal runners.
The principle underlying this method of lifting heavily bodies is quickly appreciated if one considers the following factors. The body and load rest on the longitudinal runners which, in turn, are supported by the pivot brackets at the rear. Should it be desired to lift the forward end of the body it is obvious that the best conditions will result if the supporting runners receive the force in as direct a manner as possible and not through the media of various bolts.
Continuing with the general construction of the body, the floor should in all cases be lined with sheet steel of not less than 18 S.W.G. The requirements of the front head board and hinged side boards being the same as with most other types of truck bodies, their construction follows identical lines. The tailboard requirements, however, are distinctly individual.
In the first instance a tipping body tailboard must hinge from the top. It should be easily detachable to avoid damage and the securing arrangement of a type the operation of which is unaffected by load pressure on the actual board. To facilitate fitting lift-off hinges it is sound practice to incorporate detachable rear corner posts; a mild steel round section bar upon which the tailboard is hung can then be fitted between the posts. An even better method where corner posts are incorporated is to employ what may be described as a short section of bar only, secured to each post, the lift-off hinges on the tailboard being in this case specially strengthened. The advantage gained by this arrangement is the unobstructed aperture presented when tipping, an important advantage as compared with other types. On the standard type of truck body it is customary for the tailboard to lie between the ends of the sides when closed, but with tipping bodies, carrying as they do such loads as sand and fine gravel, it is a decided improvement to hinge the board so that when it is in the closed position it completely seals’ the rear end of the body, leaving no clearances and bearing tightly against the end of the sides and along the rear face of the back bar, a generous overlap being allowed at this point.
PICTURE: Illustrating the design of the special Morris-Commercial tailboard locking device in which the hand lever is unaffected by load stresses.
Various types of devices are today employed for securing tipper tailboards but, in the writer’s experience, they are 98 per cent. alike in the respect that security is obtained only after the tailboard has been manually held in the closed position and some type of cotter or pin inserted in a slot or eye. With this arrangement difficulties frequently arise in connection with their removal at the end of a journey, because of the load having settled down en route and set up a considerable pressure on the tailboard.
It is of interest to refer to the type of security device introduced by Morris Commercial Cars Ltd. on their 4-ton end tipping model (C-type). Here the full requirements described are catered for in the respect that a specially strong toggle action clip is fitted each side. It is possible to engage the link portion of this device with the end of a stout metal channel secured to the tailboard. The handle of the clip may than be pulled round through approximately 120 degrees, thereby closing the tailboard hard up against the end of the body. A safety pin is inserted, purely as a precautionary measure, to prevent the handle from springing out. The pin can be placed into position or removed without effort under all conditions as it is in no way affected by load pressure.
It should also be noted that the complete security device is attached to the detachable corner pillars and, therefore, comes away with them should the vehicle be used as a flat platform. In the event of the tailboard not being carried on such occasions as when the vehicle may be dealing with overhanging loads the security device can be completely folded back snug against the side chock rail and secured with the safety pin.
The Tipping Gear
Without describing in detail modern end tipping gears it is extremely interesting to consider the vast improvements that are now incorporated by most manufacturers. Hand operated gears are fitted for instance with universally mounted self-aligning screws which prevent binding when the vehicle is tipped on uneven ground. Further, the screws are of the telescopic type which has the advantage of bringing them well below the height of the driver’s cab.
Power hydraulic gears also represent a distinct advance, particularly for vehicles of over 2 or 3 tons capacity. Operation of this type of gear is extremely simple, the controls being so arranged in the cab that they can be reached with ease from the driving seat, the oil reservoir being usually located under the driving seat. An individual feature included in the specification of the gear fitted to all Morris-Commercial 4-toners is a special safety catch – entirely automatic – which prevents any possibility of the body tending to self tip when unladen or in instances when load is being carried at the extreme rear end of the truck.
Bibliography and Photographic credits
The Journal of the Morris Register, Winter 1994, Vol.14 No.8