road and workshop
Page 47
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by Handyman
Bench wise: coo/it (2)
• Frederick Potts, the Freight Transport Association's new vice-chairman, has a wide experience of warehousing, transport and distribution. He is a member of the Chartered Institute of Transport, Industrial Transport and chairman of the FTA's North-Western, Merseyside and North Wales division.
As warehousing and transport controller of the William Tirnpson Group he controls more than 100 vehicles serving the company's retail outlets. He has spent his entire business life with Tim pson and started 30 years ago at branch level. Although he is now based.in the North West, his career has taken him around the country.
Frederick Potts attaches great importance to training and this is hardly surprising as it is the company's policy that all its service managers should be trained in all aspects of its business. In fact he did not become involved in transport until 1959 and was appointed controller as recently as 1969.
Unlike many own-account operators who bemoan the fact that their drivers Cannot enjoy the training facilities afforded to their professional colleagues, Timpson sends its drivers to group training associations in the North West and to the training premises of other own-account operators. And while Frederick Potts subscribes whole-heartedly to the view that good management depends largely on experience, he is just as strongly confirmed in the opinion that management training in transport is an essential ingredient in both own-account and hire and reward operation.
From 1968 to 1970 he was chairman of the FTA's technical committee and in this respect has one ambition which remains unfulfilled. He still urges the Department of the Environment to reconsider its position on axle tolerances. "I support our president, John Elliott, in this matter. Our proposals are built on experience and an awareness of the problems," he said.
While many own-account operators are considering the pros and cons of carrying for hire and reward, Timpson's transport controller has no such problem; it has always been his policy to backload his vehicles with Timpson's own goods and his spare capacity has been reduced to the minimum. In considering the method of transport to be used for any consignment he first weighs up the customer's requirements—an old-world courtesy which I thought had disappeared.
Fred's home is in Cheadle and with his wife and two children he spends most of his leisure time tramping in the North West—an apt partime for a transport 'controller with a
footwear firm, I.S.
IN an internal combustion engine heat generated in the cylinder will be first absorbed by the cylinder wall and transmitted by conduction to the coolant. Above the pistons, the cylinder head or combustion chamber and valve guides are also surrounded by water. Cooled water returning from the radiator flows through the system at a volume sufficient to remove the heat generated.
Most engines, whether overhead or side valve, have detachable, cylinder heads, and the joint is usually made with a gasket to withstand combustion pressures and to prevent coolant leakage to the cylinder bores or the atmosphere. Where water is to be transferred from head to block the joint or gasket requires special reinforcing around the transfer holes in the form of grommets. Usually these joints are copper /asbestos, but there are joints of metal or composition which do not need special attention at the water passages. However, these joints do need extra nip-up attention after fitting and to neglect this duty is to invite early failure.
Radiator core The actual radiator core has not changed too much over the years, and the construction is usually in one of two forms, tubes, or cellular. The heavier vehicle tends to use the tube type with water flowing in quantity rather than being broken up into fine droplets, as with the cellular type.
While most radiators use a top and bottom tank, there are cores with side tanks. With the top tank it is usual to find a baffle inside to distribute the water to the tubes; this also takes care of water splash or surge and loss if the system is vented to atmosphere. The bottom tank simply collects the water from the core and passes it back through the pump into the engine block, as no present-day engines could be adequately cooled without the water pump.
Most coolant pumps are based on an impeller with blades arranged to force the coolant outwards, and run on bearinks sheltered from the coolant by seals. However, as the impeller is submerged in coolant, it follows that its shaft must also be sealed against water loss, and here you have the only moving water joint in the cooling system. Few pump seals today are of the packing type, whereby a packing ring of special material is put on the spindle and then forced home into a coned housing that in turn tightens the packing around the spindle.
The modern method is the packless gland, which is really a self-adjusting seal. The main enemy to these glands (which can comprise a carbon disc rubbing under light pressure against a smooth face) is the presence of dirt or shale in the water jacket, as a single scrap of rust shale between the gland faces can cause annoying leaks.
With modern, highly efficient cooling systems there is a risk of overcooling under certain conditions and to operate an engine at full bore below its normal running temperature leads to heavy fuel consumption, power loss, and also rapid wear. Therefore, it is essential that the correct temperature is maintained at all times. Originally temperature control was effected solely by blanking off the radiator but this left a lot to be desired, and a major step forward was the built-in thermostat. Now we have radiator shutters which are controlled manually or by engine temperature.
Thermostats Two kinds of thermostat are in common use; one had a bellows filled with alcohol and designed to boil at a set temperature. At a predetermined temperature the boiling liquid creates gas pressure which expands the bellows, opening the water valve.
The other and more popular type is again like a bellows, but it is really a bimetallic coil and operates the water valve by thermal expansion. The thermostat is sited at the outlet from the cylinder heads, where generally the highest temperatures exist; the valve part of the thermostat being in the line to the radiator, acts as a door to the radiator, opening as the temperature rises, closing as it falls.
In the normal way, however, the heat is held constant by the valve opening and closing the passage to the radiator in sympathy with the thermostat coil -movement. Thus on starting from cold the thermostat valve remains closed, the water cannot reach the radiator but is passed back around the block system until hot enough to open the valve. With overheating troubles that are not explained by water shortage, slack fan belt or ill-timed engine, always look at the thermostat,' because it may be stuck in the closed position.