• That preventive maintenance is the key to trouble-free operation
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has been said and written so many times that it has become a cliche. But cliche or not, it is taken seriously at Kent Daf Trucks in Crayford where we went to follow through a service on Oaf's ATi six-wheel tractive unit.
Kent Dal Trucks, part of the Harris Commercial Group, is just over 10 years old and was formed to take over the Daf franchise in Kent, south-east London and part of Sussex when this was relinquished by Penfold Commercials. For a time, the company operated from the old Penfold premises just off the A2, but these proved too cramped and in February 1985 the company moved to its present purpose-built premises on an industrial estate at Crayford.
Since then the company has been busy rebuilding Daf business in Kent and is winning back customers as well as establishing new ones. There are plans on the new site for expanding both the offices and the workshops. The next stage, due very shortly, is the setting up of a Veeder Root tachograph centre.
There is no doubt in the minds of everyone at Kent Daf Trucks that service, both to the customer and of the trucks, is the key to winning and keeping business. As well as operating a 24-hour, seven-days-a-week heavy recovery service, the company works flexible hours in its workshops, which means that this operation can be tailored to suit the customer.
lf, for example, an operator needs to have his vehicles on the road for a busy day-time schedule, the servicing can be arranged at weekends or in the evenings. An example is the refuse collection vehicles operated by the local authority. These come in for service at the end of their normal working day and are completed and ready to start work again first thing next morning.
Kent Dal Trucks has about 15 operators running ATis at the moment, and has proved that regular preventive maintenance pays off. Since the model was launched, there have been no major problems, and not one has been off the road other than for scheduled maintenance.
1 Oils in the engine, gearbox, rear axle and hub-reduction drives are changed on a sixmonthly B service, and the engine oil filter is renewed. With the engine oil filter particularly it is important, says Kent Daf Trucks, to use the genuine Daf part, as some cheap "pattern" filters have inferior elements which do not do the job properly, and could cause premature engine wear by starving the engine of oil during the vital first few seconds after starting up from cold.
2 To avoid making a mess when draining the hub-reduction oil. a simple channel funnel was made from the cardboard carton m which the engine oil filter came. The fitter doing the job agrees that a more permanent channel could be made from sheet metal, but believes that this simple method does the job perfectly, saves cleaning a metal channel and, as an oil filter is always used on a service, the material to make a new one each time is always to hand.
The oil drain plugs on the AT have magnets built into them catch the swarf inevitably produced as the gears bed in. This is the plug from the rear axle differential on Kent Daf Trucks' ATi demonstrator which, at th time of the service, had covered just over 44,000km. Small "dust swarf such as thh is quite normal during the bedding in period, but any large metal particles from chipped teeth are a danger sign, and the component should be stripped for closer examination.
4 Maintenance on the batteries: often overlooked, or skimped, by operators doing their own servicing, yet starting and charging trouble.! are often traced to lack of battery care. Topping up must be with either distilled or de-ionised water. Many batteries have shortened lives because they are topped up with hard tap water. The connections shout', be kept greased with petroleum jelly to avoid crystals growing on them, and they should he regularly checked for tightness.
U On a B service, the wheel bearings on the first and
second steered axles are taken mi, cleaned off and checked. It is easiest to remove the hub with the wheel still attached hy using a proper lifting cradle. It is onpossible to check a bearing which is full of ;tease, so they are cleaned off before giving !hem a spin. Any roughness would mean the 5earing needed renewing. The tracks on which the bearings run are examined for roughness, pitting or Brinelling — dents vhere the rollers have been hammering. Vier checking, the bearings are repacked vith the appropriate grease and a new seal is med.
61t is false economy to try to save a bearing grease seal to re-use it. Even if it could be extracted without damage, the chances of gelling it back in and sealing properly are very small. Because a new seal is used each time, the old one is extracted the easy way — with a hammer and cold chisel. 7The dry air cleaner elements on the ATi are changed every second B service unless the vehicle is operating in exceptionally dusty conditions, in which case they are changed every B service. In normal operation, on every alternate B service the fillers are taken out and blown clean with an airline, and the filter box is cleaned out — a point sometimes missed by. operators doing their own service.
8 Accurate checking and setting of the valve rocker clearances is vital if the engine is to give its lull performance. Because of the full sound deadening in the Daf cab, noisy rockers go unnoticed by the driver, but they accelerate wear and, a point often not appreciated, too large a gap means that the valves are opening slightly late so the engine is not operating at peak efficiency. Too small a gap, however, could lead to the valves and even the seats, particularly exhaust valves and seats, burning out. 9 There is a small examination port in the brake back plates through which the linings can be inspected Jr wear. On genuine Daf linings the edges are marked to show the safe limit of wear, which is 6mm down from new. The fitter carrying out the service warns, however, that this is not always an infallible guide as it would not, for example, show uneven lining wear caused perhaps by a seized shoe.
10 There is no dryer in the air
brake system on the ATi.
Instead, there is a wet tank for water vapour separation at the front of the system on the nearside. At the base of this tank is an automatic drain valve which is checked to make sure that it is clear and operating properly.
11 On the ATi the main fuel filter and the power steering hydraulic reservoir are grouped together on the offside. The fuel filter is renewed on a B service. The power steering hydraulic reservoir has a dipstick in the top to check the level, but on this B service the top was taken off to check that the fluid was clean as well as for checking the level.
1All the slack adjusters in
' he brake system are
I released and reset as a check that none of them is seized and to make sure that there is plenty of travel left to take up brake lining wear in operation.
13 It is believed problem of wheel stud
that the breakage which has been occurring on a number of makes of vehicle over the past few years is caused by uneven torqueing of the wheel nuts or by tightening them to an incorrect torque. On the ATi B service all the wheel nuts are loosened and then torqued back to the correct figure. It was stressed to us that should a wheel have been changed on the road for any reason it is important to call in at a Daf dealer as soon afterwards as possible to have the wheel-nut torque checked,
14 Tucked away al the back of
the cab on the offside is the hydraulic reservoir for the clutch system. It is easy to overlook checking this as most of the service is done with the cab tilted. At the same time, it is convenient to check that the flexible coupling for the air intake system at the back of the cab sits squarely and properly in its base connector when the cab is lowered.
1 5Daf models, the front grill,
On the ATi, unlike earlier.
has to be lowered manualt. before the cab is tilted. On earlier models it came down automatically. Failure to lower it, as some operators have learned to their cost, invariably means a broken grille,
16 Some operators who carry
out their own servicing do not check the alignment the steered wheels either because they do ne have the equipment or because they rely on an uneven tread wear to tell them that it needs adjusting. But, as Kent Daf Trucks pointed out, by the time the tread has start4 to wear unevenly the damage has been don and the tyre's life shortened. Preventive maintenance is just that — maintenance h prevent, as far as possible, unnecessary money having to be spent. Money spent checking that all is well is often money saved.