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Lubrication: the key to gearbox care

12th September 1981
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Page 55, 12th September 1981 — Lubrication: the key to gearbox care
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Maintenance is not difficult if you follow the manual, advises Steve Gray

THE SUCCESSFUL care and maintenance of any part of a vehicle largely depends on two things: adherence to manufac turer's specifications/ recommendations and the use of common sense.

Component manufacturers don't go to the trouble and expense of producing service manuals for the sake of their health. They intend them to be a useful aid for the operator, helping him to get the best out of his vehicle by keeping all the bits and pieces up to scratch. And Turner-Spicer is one manufacturer very keen to ensure just that.

A major supplier of drivetrain components for the commercial vehicle industry, it believes that education is a vitally important aspect of its business. Unfortunately, one of its major products, gearboxes, are often the most abused and poorly maintained equipment on a lorry.

Most drivers are prepared to occasionally check the engine oil or coolant level on their vehicle, but few even think about the gearbox. They don't worry provided it doesn't let them down on the road, it's easy to change gear and it's not too noisy.

Gearboxes are, by their construction and location, more difficult to check regularly. This does not stop Turner-Spicer from recommending that the oil is inspected and brought up to the correct level every 1,000 miles. Lubrication is, says Turner-Spicer, the most important aspect of a gearbox to ensure it will function properly.

Before checking the oil level, it is vital to clean around the filter plug to prevent the ingress of dirt and grit. Gearbox oil should be changed completely every 10,000 vehicle miles or 500 hours. In particu larly severe conditions such as a dusty or dirty environment a more frequentchange is recommended.

All Spicer gearboxes have magnetic drain plugs which collect the metallic swarf generated within the box.

Turner-Spicer recommends that gearboxes are drained when they are hot. The reasons for this are perhaps obvious. When the oil is hot it has a lower viscosity and thus will run out more easily. The oil is drained to eliminate bearing surface wear caused by abrasive particles and these too are more likely to flow out when the oil is hot.

Flushing out the inside of the gearbox with flushing oil is very desirable, according to Turner-Spicer. Once the lubricating oil has been drained off, the transmission is refilled to the correct level with light flushing oil. Then the gearbox is driven for a short period in neutral without load. Old oil which is clinging inside the box and other particles are flushed out in this way.

The box is then drained of flushing oil and refilled with the correct, recommended lubricant. It is very important not to overfill the transmission. This would cause excessive oil churning, which in turn brings up the temperature of the oil. Leakage is a possible result, along with the likelihood of more difficult gear changing. Besides which, it is more expensive on oil!

Early breakdown of the oil too will result in the build-up of varnish and sludge deposits which can plug up lubrication holes and build-up on splines and bearings.

Most people abhor the thought of overhauling a gearbox, but in fact, provided a logical sequence of operations is carried out according to the service manual, it is not too difficult. The general rules to follow for dismantling the box are these: • Put the box on to a suitable fixture or stand to locate it during dis-assembly. • Ensure that there is a light hoist available to handle the main and countershafts where applicable.

• Before the box is taken apart, thoroughly clean it externally; a steam or high-pressure cleaner is best.

• Seal all openings to stop dirt or water getting into the box this might damage parts which are in good condition.

Another useful tip is to have a small tank with a wash solution in it which can be used during re-assembly to clean off components. Seals and gaskets should be renewed automatically and where special puller or other tools are specified, they should be used.

Turner-Spicer does not try to enhance sales by insisting on these tools — they are necessary for specific purposes. Otherwise general workshop tools are used.

Bearings should always be replaced says TS "as it is false economy not to do so."

Hammering on any part of the gearbox is very much frowned upon. End yoke and flanges are not only damaged but internal damage can result to such things as bearings, thrust washers, and so on.

Recovering disabled vehicles can result in potential problems for the gearbox. It is essential when the engine is out of action that either the broken down truck is suspend towed at the rear or the propshaft is removed atthe axle end. Failure to do this can cause damage as the propshaft will still rotate but the gears will not, and so there is no lubrication.

An area often missed during maintenance is the gear selection linkage. Many modern tiltcab trucks have long and complex linkages with a number of joints. These should be lubricated and checked regularly and any worn rubber bushes replaced.

However, following the correct maintenance and overhaul steps does not obviate one of the principal problems — that of driver error and abuse.

Most heavy vehicle transmissions have a clutch brake to stop gear rotation for initial engagement. This stops the gears from clashing, with the inevitable accelerated wear possibility. Drivers should be taught to use the clutch brake correctly by depressing the pedal fully to allow it to work.

By the same token, education into the finer points of non synchronised gear selection, including the right way to double de-clutch, will pay dividends.

But double de-clutching on synchromesh gearboxes must be very much discouraged. Far from reducing wear or load on the synchronisers, it actually exacerbates it.

While gearboxes are "out of sight, out of mind" clutches are probably even more so.

The general rule for clutches — apart from the automatically adjusted variety — is not to leave adjustment until too late. By then the damage has been done. Using the vehicle manufacturer's handbook to ascertain the correct clearance and frequency of adjustment saves time and effort.

Remember, too, that linkages are different, and some makers build the free play into the system. But the linkage is the make or break of the clutch operation.

Turner-Spicer angle-spring clutches can be stripped and rebuilt without specialist equipment. When rebuilt they are completely balanced — the only ones in their class. When re-assembling, the drive pins should be aligned and the bolts tightened in sequence. Next the linkage should be corrected according to the maker's recommendation and the release bearing gap — internal adjustment — should be checked.

There should be 3mm free play between yoke and bearing. If the system is hydrostatic the equivalent should be at the slave cylinder or servo. The release bearing should contact the clutch brake when the clutch pedal is 25mm (1 in) from the floor in the cab. The whole operation should be checked to make sure the system goes through a complete stroke.

It is important, says TurnerSpicer, to educate the driver about clutches in the same way as gearboxes. He should be aware when the clutch needs replacing. If an automatic clutch is near the end of its time, a few pumps on the clutch pedal will enable the vehicle to be driven.

When changing clutch assemblies — the drive-pins should also be replaced. A check on the flywheel to spot cracks and burnt areas is a good idea too. Ceramic disc materials are an option from TurnerSpicer, and although they command a price per cent premium they offer a greater life --up to one third more.

In addition to cost savings, they require less changing load and are good in excess heat. Drive joints, because of their relative simplicity, require little maintenance. Modern TurnerSpicer joints take more torque through a smaller joint which enables a smaller drive shaft to be fitted. The joints have a nonreturn valve which allows grease in but not out. It should obviously be working properly and kept so.

Turner-Spicer's yoke drive system not only can eliminate companion flanges, and thereby save weight — up to 241b. When installing the joints they should be thoroughly purged and this applies during routine servicing to get rid of old grease.

Pt-o's are much the same as gearboxes when it comes to maintenance. Cleanliness is vital, as dirt will soon cause excess wear. Control cables and units should be kept free and working properly.

Good driver training will prevent the pt-o from being left engaged inadvertently while the vehicle is driven normally. This puts excess torque loadings on to the pt-o for which it was never designed. training of personnel on the necessary actions needed in a fire, and the keeping of records; limits to numbers of people; and any other relevant fire precautions.

All this is fine, but these are precautions designed to deal with fires in premises once they have started. The real answer, of course, is to prevent fires from starting in the first place.

This is easier said than done. Unless you can keep your eye on every member of staff every minute of the day it's impossible to stop the really determined firebug from smoking +A there are flammable liq such as petrol and paint ners; throwing lighted mai away carelessly; and lei heaters on after they've fini work for the day.

Protective measures cai implemented, however, v will go some way tow. lessening the threat. Flamnr materials should be kept fire-resistant and purpose store, away from the workshop or factory area. quantity kept in the work itself should be reduced minimum and staff shoul impressed with the need t seal or re-cap containers.

Waste flammable matl should be disposed of and out of harm's way — nc around in open jars or can gine oil, though not immedi flammable, will burn quite pily once a fire has startec will add considerably to spread of the conflagration.

Drainers should either t the safety type, which are resistant, or if an open ty used, the oil should be ti away as soon as it has drained. If used oil is storE the premises for sale or rE the storage area should be away from the main builc Remember too, that oil dri from petrol-engined veh invariably has a quantity c trol in it, making it more flar ble.

Areas of high risk — suf spray booths or even workshop itself — shoul kept as no-smoking areas.

It's a good idea to provide with a separate eating al smoking area, away vehicles or materials like catch fire. It should be ma fire-resistant as possible, plenty of ashtrays.

Office staff can be ju: :ss as those on the shopThey can throw lighted Ales into paper-filled waste or leave them slowly rig in an ashtray, ready to Ito a desk or floor. Plenty of ring signs about such ds are the order of the day. you can't blame staff for thing. Electrical fires are on and yet are one of the st to prevent. Frayed 5, damaged light fittings or appliances must be red or repaired. The use of Iven power tools, such as drills, will cut down risks, too.

All these precautionary measures though vitally important, must be backed up with positive protection devices — obviously the most important of these being actual fire-extinguishing devices.

These must be suitable for the types of fire they may have to extinguish. So, an ordinary water extinguisher is useless for a petrol fire — it will just spread it. Foam or a blanket is the only answer. Electrical fires need a gas-type extinguisher to prevent further shorting.

The installation of automatic sprinkler systems is fine for offices, if a trifle expensive.

On the warning front, larger purpose-built offices have integrated systems, some including a vocal alarm system. However, less-affluent organisations can give themselves a measure of protection by installing individual smoke alarms.

Costing only a few pounds, these are readily installed by a couple of screws into the ceiling. They give off a loud buzz if a fire starts. However, they're battery operated invariably, so should have the batteries changed at regular intervals.

In comparison to vehicles, premises, be they garage workshops, offices or warehouses, are relatively easy to protect. Vehicles out on the road, in all kinds of different operating conditions, are much more difficult proposition.

Luckily, the incidence of selfigniting fires is low, mainly due to modern vehicle wiring. Having said that, fires do still happen and can be costly. Not only is the vehicle damaged, often beyond repair, but the load is usually ruined too. Costly downtime while the lorry is repaired, as well as the driver's wages, are the financial burdens to be expected.

However, there are many ways in which an operator can help himself prevent fires starting. Any additional equipment wiring should be properly fused and tidily put together to prevent sparking — this applies to radios, spot lights and other ancillaries. A battery isolator switch makes good sense, not just for vehicles needing to conform to petroleum regulations. Petrol-engined vehicles should be regularly checked to ensure fuel lines are in good condition and unions are tight. Carburettor gaskets can and do leak. They should be replaced if suspect.

Obviously most of the inherent vehicle security comes from the original design where fire prevention devices such as wiring protection — such as that on the Ford Cargo — is built in.

However, fires can still happen, so it makes good sense to carry an extinguisher on board to deal with them.

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