TAILORING LEET FOR BAKERY DELIVERY
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By P. A. C. BROCKINGT
A.M.I.Mech.E.
ON an. average working day, the intake of flour from pneumatically discharged vehicles at the new Mothers Pride bakery of Enterprise Bakeries Ltd., Stoneb ridge Highway, Coventry, is approximately 30 tons, and by the following, morning about 75,000 loaves of bread are ready for delivery by a modern fleet of vehicles within an area of 40 miles. Confectionery is supplied for combined distribution with the loaves by other associated companies in the British Bakeries group. The Coventry bakery was officially opened by Lord Rank, chairman of the group, on September 20 of this year, and is claimed to be the most modern of its type in Europe.
Fed from two 50-ton silos, one completely automatic and one semi-automatic production line have a joint capacity of 4,000 loaves an hour, and loads are transferred to an airconditioned dispatch area which can accommodate over 100 delivery vehicles of normal size. This has an area of 28,0000 sq. ft. and has the second largest clear-spanned roof in thp country. The delivery fleet is under the control of the regional transport manager who is directly responsible for the types of vehicle and bodywork employed, the use of special equipment and for planning maintenance procedures. Although a number of basic operating principles are applicable to all the fleets of the group (comprising many thousands of vehicles), a high degree of local autonomy in the organization of transport facilities is regarded as essential to efficient planning and distribution.
Continual Experiments Easy-access cabs, lightweight bodywork that gives freedom from condensation and racks that can be adjusted to accommodate trays of different sizes are features of all the latest vehicles in the fleet, and in due course every van (other than the electrics) will be powered by a diesel engine. Experimental work is being continually undertaken with the full co-operation of vehicle and equipment makers with the object of reducing running, costs and improving operational flexibility, and an .accurate costing system enables the results obtained to be evaluated in detail. The use of automatic gearboxes and the application of various temperature-control devices are included in current experiments, and two vans are fitted with test equipment to analyse the performance of the electrical units under typical service conditions. • Vehicles engaged in wholesale:deliveries to shops and industrial premises mainly comprise Thames 2-ton and 3-ton 4D-erigined semi-forward-control vans; some of these are based on the latest Trader low-height chassis whilst four are equipped 034 with Garner-converted easy-access cabs. Because a standard normal-control vehicle affords ease of entry without structural modification, it would be preferred to the forward-control type if its length were not some 2 to 3 ft. greater for a given loadcapacity. This would increase parking difficulties in the street and also the undercover parking space required at the bakery.
The bodies of the wholesale vehicles are based on a framework of aluminium, which is clad with glass fibre colourimpregnated side panels and a translucent one-piece plastics roof. A separate confectionery compartment is located at the front of the body and is fitted with inset sliding doors on each side. The rear door is of the lift-up type with spring-loaded counter-balancing rams and is used in conjunction with two
lower doors of the split-tailgate type. This combination provides speed of working and undercover protection for the operative in• inclement weather. Both piston-engined and battery-electric vehicles are employed for retail deliveries, the former being Austin or Morris 16-18-cwt. vans and the latter mainly Morris' on 1-tonners fitted with high-speed motors. The special bodies of the retail vehicles are of particular interest in that the colourimpregnated sides and roof are unstressed, structural strength being provided by the aluminium racking. Built to the specifi :ation of the transport department by the MetropolitanDammell company, a body comprises a number of jig-built ;ections which include the two sides, cab doors, rear doors, he front sections, confectionery cupboard door and roof., the ast-named being fitted with an upper section, mounted on amts, which affords an air space of 1-5 in. for protection against he sun's rays without materially reducing the translucency of he roof.
Originally, the plastics panels were reinforced with bondedn timber members, but these tended to warp and have been eplaced by steel inserts. Although adding fractionally to werall weight, the use of steel promotes rigidity, and the stnicure provides a saving of around 2 cwt., compared with plastics vane's with light-alloy framing. Because they are totally :nclosed, the steel sections cannot rust, and the glass fibre mnels are not only immune from corrosion but reduce conlensation. Moreover, the panels have a high-gloss finish, :nd it is considered that painting costs should be eliminated for he vehicle's normal life of 9 to 10 years, apart from that iecessitated by accidental damage. Steel brackets are bonded nto the side, roof and front sections which are assembled vith rust-proof bolts. Any section can, therefore, be easily eplaced in the event of damage. A coating of polystyrene esin is applied to the steel floor to prevent corroOon and to acilitate washing out. This is white impregnated in the nterests of cleanliness, hygiene and appearance.
Designed to accommodate a wide variety of tray sizes in ;iven box dimensions (covering every type of tray employed )31 the British Bakeries group), the special aluminium racks ncorporate detachable members that can be pegged in different iositions to longitudinal runners and end plates. Changing he racks 'occupies about 30 min., all the trays being of the pen-wire type constructed of 0.25-in. and 0.125-in_ rod.
Such is the speed of working on a typical retail-delivery run that equipment makers have been asked to develop a combined ignition-and-starter switch for petrol engines and a solenoidcontrolled injection-pump stop control for diesel engines. All cabs are fitted with sun visors and interior lights.
The Morrison battery electrics are equipped with a fourspeed controller giving a maximum speed in excess of 20 m.p.h. and have a useful operating radius of 25 miles. Of the jig-builtsection type, the plastics body is .basically similar to that fitted to the B.M.C. 16-18-cwt, chassis, and the cab is equipped with jack-knife doors. Ease of access. and a large glazing area are particularly welcome features of the design.
First cost of an electric is 50 per cent higher than the cost of an equivalent diesel-engined van, but operating cost is lower by over 30 per cent, and its life expectancy is 15 years compared with a diesel-vehicle life of 10 years. The reduced speed of the electric makes little difference to delivery time provided that the mileage is small.
Vans in the retail fleet powered by the I3.M.C. 1.5-litre diesel engine average more than 28 m.p.g., whereas the petrol-driven version of this engine in similar vehicles gives a consumption of 17 m.p.g. Certain associated companies use Perkins-engined Ford 15-cwt. vans for retail delivery, which 'return an overall average consumption of about 24 m.p.g., compared with 15 m.p.g. averaged by the original petrol-engined vans, powered by Ford 1703 units. Employed for shorter runs, petrol-engined retail vehicles cover about 220 miles in the week, whilst the weekly mileage of the diesel-engincd vans is around 260 miles. During a typical working day a retail van makes at least 120 stops and starts compared with a stop-start frequency of 50-60 in the day of a diesel-engined wholesale vehicle, the average mileage of which is approximately 360 a week.
Although the annual mileage of the retail vehicles rarely exceeds 13,000, the use of diesel engines affords a fuel saving of about £40 in the I2-month period, and the additional first cost of the units is recovered in two to three years. Moreover, the governed speed of the diesels gives closer control of maximum road speed and this is reflected in reduced wear of brakes and tyres. The petrol-engined vehicles offer the advantages of quietness and increased power.
Because of the concentrated stop-start work of the retail vans, the wear-and-tear rate of gearboxes and clutches is very high, and it is normally necessary to recondition these components twice in a mileage of about 30.000. It is, therefore, the more remarkable that a Thames 15-cwt. retail van, fitted with a Hobbs fully automatic epicyclic gearbox, has covered 33,000 miles without attention to the unit. A B.M.C. van of similar capacity is equipped with a Borg-Warner 35 torqueconverter type of automatic gearbox and this has so far covered about 13,000 miles without trouble.
In both cases, the gearbox offers ease of control, and if an automatic transmission were available at a reasonable cost, it would be specified as standard equipment for new vehicles. The fuel consumption of the van fitted with the Hobbs gearbox is more favourable than that of the vehicle equipped with the Borg-Warner transmission, but the latter provides smoother Operation.
Two .Vehicles Fully Instrumented " In close co-operation with the _Lucas company, two vehicles have been fully instrumented to provide records of battery• input and output, generator performance, lamp load, average speed and the number of stops and starts. The data collected will in due course enable modifications to be made to improve the efficiency of the electrical components, should this be proved necessary.
The importance of maintaining the optimum working temperature of the power units is fully appreciated, and in winter part of the radiator is blanked-off and, in some cases, fan blades are removed. Varivane automatic-shutter equipment has been applied to a number of vehicles experimentally, whichseals the radiator up to a temperature of 172 degrees F (77.7 degrees C) and gives an all-the-year-round improvement in fuel consumption. It also eliminates cold sludging of the lubricant, and this is expected to reduce cylinder-bore and piston wear.
In a second experimental application, the fan is driven by a Lucas electric motor which is controlled by a switch connected to a thermostat in the bottom tank of the radiator. The -thermostat immobilizes the fan at all temperatures below 172 degrees F and thus reduces fan losses as well as increasing
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the warming-up rate and the average working temperature. All power units are lubricated with a Castrol S.A.E., 20 Supplement 1 oil, blended to the specification of the company, and only two grades of _gear oil are employed for the transmission, one for the gearboxes and one for the axles. The use of a. Supplement• I engine lubricant has _substantially reduced bore wear and the use of one grade for all units (including car engines) greatly facilitates the storage problem. It also-obviates use of an incorrect grade. An anti-freeze solution containing a corrosion inhibitor is added to the coolant in the winter, and in summer an inhibitor is used without an anti-freeze .ingredient. The same type of solution would be employed throughout the year if itwere possible to make routine checks of its properties in a simple way to avoid continued use of a solution with excessive acidity or alkalinity. Tyres of Dunlop or Michelin manufacture with rigid-breaker treads are specified for all new vehicles, Dunlop covers being fitted to the B.M.C. vans and Michelins to the Thames. This type of tyre affords an improvement in useful life of at least 50 per cent arid, of particular importance to the retail vehicles, the increase in steering torque is negligible, accurate tests having shown that it is less than 4 per cent. Covers are remoulded one or mOre times according to the condition of the carcass, and mileage life is increased by each remoulding process by about two-thirds. .
Maintenance Procedure Maintenance procedure is controlled by a budgetary system based on the anticipated life cycle of components, which is derived from past experience and is applicable to each type of chassis individually. Routine preventive maintenance is practised in the form of a monthly dock for greasing and a thorough check of the engine and running-gear components by a qualified mechanic. At three-monthly intervals every vehicle is docked for a longer period, a form is completed showing the condition of every component and repairs are immediately authorized in accordance with this report. The return of vans to the depot by 4 p.m. normally enables an emergency repair to •be completed in readiness for the following day's run.
Whilst it is customary to replace a worn engine by a factoryreconditioned unit:from stock, intermediate Overhauls are performed in the workshops (including the fitting of new pistons, bearing, shells and so on) and a complete overhaul is undertaken in an emergency. Vehicle serviceability averages 90 per cent, an average of two to three vehicles being usually in the workshops for repainting, in addition to those undergoing routine maintenance. The garage features a sunken workshop with three pits, a Laycock four-post lift and a comprehensive range of equipment includes a Dunedin injection analyser and a Lucas beam setter.
An undercover bay is equipped with a Dawson rotating-brush type washer with automatic control, which enables a vehicle to be cleaned in three to five minutes (a brush. is applied manually to the front and rear panels), and in an adjacent bay fuel and lubricant dispensing nozzles-with automatic cut-off control are supplied from underground tanks. Water is .available from a reeled hose and no containers are therefore required for handling of the various-liquids.
A detergent of the non-ionic type is bled into the washing water, which has no deleterious effect on the plastics bodies. Tests with an ionic-type detergent showed that it was more prone to cause fading of colour-impregnated panels.
Although existing types of bodywork are near-ideal for bakery deliveries (the easy access to the cabs of the electric vehicles and their generous glazing area are features that could, with advantage, be applied to the piston-engined vehicles), it is considered that a completely different type of chassis could Well be developed which would be a boon to the majority of light-delivery operators. In the interests of body space, the power unit would be located under the floor, and would preferably be a two-stroke unit of the air-cooled type, coupled to an automatic gearbox. This would have a good power-to-weight ratio, would be easy to maintain and which would operate without freezing or plumbing troubles. The suspension would be of the constant-periodicity type, which would obviate damage to fragile confectionary being carried in a lightly, loaded van.