Grease to Go

“Change the oil and grease the bearings” is part of maintenance lexicon. And what could be simpler than shooting some grease into the zerk fittings underneath a rig? On a truck or tractor, it’s part of the overall lube-changing routine, also known as an “A” check in most fleets’ preventive maintenance books. On a trailer, it’s usually done on a time basis.

Greasing the chassis may be simple, but it doesn’t always get done right or on time. On a tractor, there can be more than 30 bearings that need lubrication: 20 on the front end, including steering arms, kingpins, spring hangers and the like; two at each brake (one each for the S-cam and the automatic slack adjuster); and two to six on a fifth wheel (including several in the grooves of the plate’s surface). It’s easy for the guy with the gun to miss one or two.

Time-wise, a rig may be out on the road longer than expected, so a lube job is catch-as-catch-can whenever the truck makes it to the shop. Moreover, truck owners are moving toward extended oil-change intervals, which may double the distance between service stops. That’s fine for the engine, but it may cause you to skip scheduled maintenance for the chassis.

Do so and you’re inviting trouble. When front-end joints, brake slack adjusters, spring hangers, and other parts with sensitive bearings and metal-to-metal interfaces begin going dry, their performance deteriorates and they fatigue prematurely. Grease also acts as a barrier to dirt and moisture. When the lubricant is not there, these contaminants enter and wear increases.

When the vehicle does get lubed, the maintenance man usually shoots too much grease into each fitting. He pumps his grease gun until grease oozes out the other end. He may wipe off the zerk fitting and the excess grease on the part, but that grease is discarded along with the rag. If you waste only one pound of grease per heavy truck each year … well, add it up.

MAN OR MACHINE?

That’s why some fleets and even owner-operators have turned to automatic chassis lubrication systems. An autolube system works several times a day, every day the vehicle is operated. It shoots exactly the correct amount of grease into each fitting. This means a part never starves for lubricant, contaminants are kept out, and the part performs like it should for a longer period of time.

The bottom line: lube isn’t wasted, and since the autolube system is connected to virtually everything that requires greasing (save for U-joints on spinning drive shafts), it can’t forget a fitting, either. Their manufacturers claim they can quickly pay for themselves in saved manpower and downtime, if not added resale value to the vehicle.

Individually, an autolube system’s parts are fairly simple. But there may be quite a few of each part because they must reach many points on the chassis. There are several autolube systems on the market. While they differ in design details, they share a similar basic operating concept. An autolube’s basic components include:

* A reservoir to hold the lubricant. * An air or electrical pump to push it. * A timer to activate a main pump. * A set of distributors that meter the lubricant in the proper amounts and push it to each bearing on the chassis.

Usually, a modular approach is used in an installation. A primary valve and line feed grease to secondary metering units, each of which is plumbed to one or more lube points. Hose fittings replace your zerk fittings.

During the installation process, the system is calibrated to ensure that each fitting gets the correct amount of grease. A fraction of an ounce of grease-equivalent to less than one lever stroke of a hand-operated grease gun-is usually all you need to have pumped into a fitting each time. This is enough because the fittings are greased more often.

You can set the timer to meet the requirements of your operation. This might range from twice a day to once every two hours. Most timers run whenever the rig’s ignition is switched on, so the system will cycle while the engine idles as well as when the rig is moving down the road. Prolonged idling could therefore waste some grease (but smart managers and drivers limit idling as much as possible, anyway).

The reservoir generally holds several pounds of grease, which should be enough for a month or more of operation. Manufacturers say replenishing the reservoir is one of the few maintenance requirements of the autolube system; the other is periodically inspecting it to be sure it’s working. The timer usually has a “test” position for such inspections.

Main pumps come in two types. Pneumatically powered pumps are relatively simple and useful on trucks with air systems. Electric pumps allow installation of an autolube system on vehicles with or without an air system, such as medium- and even light-duty trucks.

Autolube systems are generally sold for use on powered vehicles, as well as on construction machinery and other equipment. They’re not often found on highway trailers: most fleets shy away from the upcharge, and there are relatively few lubable fittings on a trailer. However, manufacturers are bringing low-cost, reliable automatic greasing systems to market, using the trailer’s air and/or electricity supply from the tractor.

An economical alternative-for trailers or tractors-is a manually operated collector system that eliminates the pump and timer but retains a common valve body, from which lines go to points to be lubed. A serviceman places a grease gun on a zerk on the valve body and pumps grease into all points at once. No fitting will be missed when the greasing gets done.

However, a human being still has to remember to follow whatever service interval you choose. And if he doesn’t wipe away excess grease and dirt, the system can become blocked. A filter may help solve the problem, but it may also add to the system’s expense and maintenance.

If you do buy any type of autolube system, find out what type of grease should be used, and use it. Certain moly greases (typically over 5%) may or may not work well in a given system, especially in very cold weather. For highway equipment, a high-quality 00-grease will do the job. Autolube systems are available to accommodate a heavier lubricant if that’s what you need.

One argument against using an automatic lubing system is its price-up to $2500 installed (or several hundred dollars for a manual collector system). The price, however, may be offset by an increase in the vehicle’s resale value because the buyer can feel assured that the components have been properly maintained.

There’s also something to be said for greasing a truck by hand. You can argue that while the guy is under there he can look for other problems, like loose or broken parts. That may work if you’re the one in the coveralls, but at most shops the person under the truck doing the greasing is not the lead mechanic, or even a close No. 2. And he’s only human, after all.

The most plausible reason for not using autolube systems may come if you trade in vehicles often, because wear on components from occasionally skipped greasings may not show up until after the vehicle is out of your hands. At that point, the trucks are someone else’s problem.