MAKING NGINES LIVE I EVER
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CONCERNS engaged in motor repir and distribution which have specialized from their inception in commercial-vehicle work, are a rarity. A partnership, however, coming within this definition, was formed in 1928, and from that date Messrs. Ford and Slater, Gwendolen Road, Leicester, the firm in point, have justified their fore' sight and courage in embarking upon that course. Their very first job was the overhaul of a small fleet of buses. Since then there has never been a day in which there has not been enough and to spare of work for them to do.
It would not be true to state that they have entirely neglected the private-car side of the motor business. It has • always been regarded, however, as of secondary importance, and for the year just past, or thereabouts, no car work at all has been accepted, or will be until the war is over.
The policy of the firm from the outset has been to place service before sales, in order of importance. It is reflected in the comprehensive range of equipment to be found in their works. For example, there are two Heenan and Fronde dynamometers, on one or other of which every engine that is overhauled is thoroughly tested, for power, consumption, torque, etc., according to the methods current in the test shops of the respective manufacturers.
Operations Involved in Reconditioning Perhaps the best way of demonstrating the extent to which this establishment is furnished with equipment for repairs and maintenance of commercial vehicles is briefly to schedule the. sequence of operations carried out in overhauling an engine, referring at each stage to the equipment used.
An engine for overhaul, immediately on its removal from the chassis, is placed in a portable engine stand of orthodox type. It is chemically cleaned externally and then thoroughly washed by means of a Lay-cock high-pressure washer.
The unit is next stripped of all parts, which are placed in steel trays, chemically cleaned, and then examined in detail for wear. The cylinder block remains in the engine stand and is not removed therefrom until the overhaul is completed and the engine finally assembled and ready for teit. Crankshafts and all other parts which may need it are crack-detected on a Johnson Fel machine.
If the engine is to be rebored, a set of toughened sleeves which, in experience, have been found to be exceptionally long wearing, are selected. The cylinder block is bored by Van Norman equipment. It is then honed. The sleeves are inserted and, as 4 result of the honing, the contact between sleeve and cylinder bore is particularly close,, so that good heat conductivity is bound to result. Subsequently the sleeves are. bored and honed to standard size.
Extreme accuracy in the% operations is a characteristic A24 • • of the work done. In the ease of a block upon which this operation had just been completed we took measurements, using a clot-type cylinder gauge, and the maximum variation from top to bottom of each bore and from cylinder to cylinder was plus or :minus 0.00025 in.
It is the standard policy of this firm that reboring and the fitting of over-size pistons is never carried out on oil engines. Cylinders are always sleeved and finished to the original works dimensions. Oversize pistons or rings are not stocked.
If the original pistons, on inspection, prove to be satisfactory, the grooves for the rings are machined and special new rings fitted. Connecting rods are tested in a jig for alignment and big ends bored on a K.B. machine.
Main bearings are line-bored by a Newton main-bearing
• boring tool, the advantage of which, according to Mr. Ford, is the rapidity of operation and accuracy of clearances. In these operations prede‘termined clearances are set and adhered to so that hand-fitting and guess work are entirely eliminated in re-erection.
Uniformity in Tightening Bolts All bearing bolts, also cylinder-head nuts, are tightened by tension wrench so that the degree of tightening is known and is consistent throughout. An interesting point arose in discussing this particular aspect of overhauls witli Mr. Ford. He told us that it is his experience that, after 'main bearings and big ends are bored, with the bolts tightened as just described, it is found that, when assembling, any divergencies from this standard of tightness are immediately reflected in the fit of the journals or crankpins in the bearings or big ends, respectively.
Valves and valve seats are trued in a Van Norman grinder, Atomizers are thoroughly overhauled and the needle valves lapped to their seats. In this connection, incidentally, is to be noted the use of a special machine to facilitate the lapping-in . of atomizer needles—a job which ordinarily, when manually performed, is a tedious process. The special machine considerably shortens the time needed for the operation besides improving the efficiency of the work done.
When these detailed operations are completed and all • parts assembled, the engine is. taken to a Heenan and Froude dynamometer and is run on test, adjustments being made until the test readings agree with those obtained in the manufacturer's works. Consumption figures as well as those for output, etc., are recorded and checked.
An interesting point is that during this running-in and testing a Phillips magnetic filter is inserted in the engine-oil circulation system. This extracts all ferrous metal dust from the oil and ensures absolute cleanliness. In the case of a Perkins P6 engine, this filter is located between the Tecalemit filter and the main oil gallery. Having in mind the care and cleanliness that are a feature of engine assembly operations after overhaul, it is astonishing what an amount of metal dust ie extracted from the oil by this magnetic filter. That, in itself, is justification for the use of this equipment and indicates the desirability of its employment, when engines have been overhauled, before they are released to the customer. • An important department of the garage is the welding shop, in which a Lincoln d.c. "arc welder is installed. This is used for a wide variety of work, as, for example, the rebuilding of starter rings. In such a case broken or worn teeth are rebuilt with nickel-chrome and it is claimed that once thisoperation has been completed the trouble likely to be experienced subsequently in the way of wear or damage is almost negligible.
The same plant is used for engine conversions as when an oil engine is being installed to replace a petrol unit and some modification of the clutch housing is involved. Clutch housings are fabricated, with the aid of the welder, and economy in time and materials is thus effected.
The need for cleanliness in all these operations is particularly stressed. All benches are metal topped, and paraffin is freely used for cleaning, whilst compressed air, for drying, is available throughout the premises, air lines fed by a Tecalemit compressor being placed at all assembly points.
Mr. Ford told us that there is one man engaged throughout the week exclusively in keeping the place clean. He may not do any other work and the result of this policy is evident the moment one puts foot inside the workshops.
For the Operative's Benefit Considerable ingenuity has been exercised in the manufacture of garage equipment designed to be adaptable to the firm's own particular requirements. A simple instance, but one that is none the less noteworthy, is a portable bench, complete with vice and other essentials, which any workman may use and take to any part of the premises. A rather ingenious feature is that in its construction provision has been made for accommodating a drawer, but no drawer is provided. All the various workmen's drawers in the benches are made to standard size and any one of them can be removed from the fixed bench, placed in the portable bench and locked as desired.
A garage crane, which figures in one of the accompanying illustrations, is also an example of the firm's ingenuity. It is a most satisfactory piece of equipment and has actually been built, so far as its operative mechanism is concerned, from the steering gear of a Vulcan lorry and a-telescopicscrew tipping gear.
A feature which ive should think must be unique in an establishment of this size is the inclusion of a training school for apprentices. This is an entirely separate department, equipped with grinding machine, drill, benches, vices and essential small tools. Youths desiring to enter the business go straight into this school and are relieved, on the one hand, from the necessity of catering for the tea requirements of the men in the shop and, on the other, from attendance at night school. A comprehensive and condensed curriculum has been arranged by Mr. T. Slater, who himself takes charge of the school and lectures the students on all such essential subjects' as the kinds of metal employed in automobile engineering, their characteristics and applications, the proper use of tools, the mechanism of an automobile, the meaning of the various terms used in motor engineering, the testing of engines, and the essential points to bear in mind in maintenance.
Each student, on entering the school, is presented with a steel folding tool box and a full equipment of all small tools—spanners, screw .drivers, pliers, rules, callipers and so on. leis a rigid rule that no student must lend or borrow a ,tool. From the psycho logical aspect alone this gift of tool equipment is one which can be com mended. It is obvious that these. youngsters must get a tremendous kick on being provided,on their entry into business, with equipment of this nature.
Messrs. Ford and Slater are enthu'siastic about the Perkins Perpetuity
Plan. This is well known to users of .Perkins P6 engines and to agents for F. Perkins, Ltd., throughout the kingdom, but it may not be familiar to all those who read this article and a. brief description, therefore, is advisable, Regular readers may be aware of some of its outstanding features by reason of earlier references we have made to the scheme since it was originally put into practice, but to refresh their memories will do no harm.
The plan was introduced in September, 1938. It is designed to eliminate the objectiem to the use of oil engines in the lighter types of chassis, on the ground that, owing to the much higher initial cost of an oil engine and the corresponding increase in the item " depreciation " of operating cost, it is impossible, by economies in expenditure on fuel, to offset the greater cost of the oil engine, unless a considerable mileage be covered in the course of the year's operations.
The Perkins Perpetuity Plan is, in effect, an engine replacement scheme, with this important difference from ordinary schemes of this sort. It operates ,entirely to eliminate the item " depreciation " so far as the power unit is concerned and it achieves that end in this way. Engine replacement is offered at a fixed price; to-day that price is around £130, but—and this is where the Perkins engine replacement scheme differs from all others—the replacement engiue carries the same guarantee as the new one and that guarantee is carried forward from replacement engine to replacement engine, all along the line, so that, for all practical purposes, the engine may be said to live for-ever. • • Engine Replacement In a Few Hours All that an operator has to do when his engine needs an overhaul is to take it to an authorized Perkins agent, such as Messrs. Ford and Slater, and to ask for it to be replaced by a reconditioned engine at the standard price. The substitution is effected in a few hours and the vehicle is driven away with an engine that is, to all intents and purposes, perfectly new from the mechanical angle and in respect of guarantee.
• Now here is an important piece of news. The Ministry of Supply has expressed, although perhaps indirectly, approval of the Perkins Perpetuity Plan, for it has released four Perkins P6 -engines to Messrs. FrArd and Slater for use simply and -solely as replacement units so that the firm may be in a position effectively to operate the plan, The firm have had to sign.an agreement not to utilize any one of these four engines except as a replacement unit. That is very significant.
Nor is it :unimportant that the firm have sufficient confidence in the Perpetuity Plan to be prepared to lay out the capital involved ix the purchase of four new Perkins P6 engines together with the spare parts which an agent must have available if the plan. is to be operated effectively by him.
Obviously it is not enough merely to have a pool of spare engines for replacement purposes. There must also be pools of spare parts with which to recondition and rebuild the engines which have been replaced. The agent actually holds in stock not only a supply of parts but also a number of spare assemblies—cylinder-head ind cylinder. block units, crankshafts, injection components, dynamos, other auxiliaries, and so forth, Provision for all processes essential to the effective operation of the Perkins Perpetuity Plan. has been made by Messrs. Ford and Slater, so that any of their customers, in a few hours, call have an engine replaced by another one which, as we have said, carries the full guarantee and is, in effect, a new unit. Thus the item " depreciation " disappears from his schedule of operating costs so far as his engine is concerned.