Automatic Chassis Lube Systems (ACLS)

A vehicle with ACLS delivers a periodic, uniform shot of grease to critical points as often as every few minutes. That helps offset incomplete or inadequate lubrication during PMs and in some fleets has reportedly helped components such as steering kingpins and other components last through the vehicle’s life.

An advantage of the mobile system versus stationary lubing is that the continuous addition of fresh lubricant tends to force out old, contaminated lubricant. To distribute grease, on-board lube systems use the same basic components:

A reservoir holds the supply of grease to be distributed.

A pump delivers the lubricant through a network of grease lines. Metering valves dispense the grease.

An automatic timer mechanism tells the pumpand- valve system when to pump grease.

An electrical motor or other power source (the truck’s air system is the most widely used).

Air-Driven Systems. In air-driven systems, progressive feeders, piston distributors, or metering valves at the end of the dispensing lines are strategically located at the chassis’ multiple grease points; major suspension points; shackle pins; brake camshafts; slack adjusters; clutch releases; steering linkages (tie-rod ends, drag links); kingpins, and the fifth wheel (pivot points, fifth wheel plate, slider rails). The pump in air-driven systems is activated by a solenoid valve.

Motor-Driven Systems. Air or electric motordriven systems use a multioutlet pump and no secondary distribution parts. The grease is metered directly at the pump. A third type of system, using a single outlet, electric-driven gear pump, uses a secondary system of metering valves, piston distributors or progressive feeders, like the truck air system-driven setup. Most U-joints must still be lubed manually. This creates a convenient maintenance interval for the system itself. While technicians are manually lubing the U-joints, they can fill the automatic system reservoir, which should last for 2 to 4 months, and at the same time check system lines to ensure they are in place and functioning properly.

Distribution. One system can be configured to lubricate more than thirty-two points, including steering kingpins, spring pins, brake “S”-cams, brake slack adjusters, the clutch, shift shaft linkage, and fifth wheel plates. The unit’s integrated pump, powered by the truck air supply circuit, feeds grease through a main line to modules that serve groups of lube points (left and right front, rear axles, fifth wheel, and suspension). The modules are fitted with different-sized meters that feed varying amounts of grease to individual points through distribution lines. (Nonmodule systems require a separate line for each individual lube point.)

System Cycling. A 12- or 24-volt DC solenoid controller on this particular system, working in conjunction with the pump, initiates lube cycles at regular intervals. Adjustment of a simple knob on the face of a small, solid-state timer programs the controller to trigger a lube cycle anywhere from once every 6 hours to as often as every ½ hour. The timer’s built-in memory retains elapsed cycle time when the ignition is switched off and resumes when it is switched back on. The grease reservoir typically holds 10 pounds of lubricant, or enough to last a truck in an average linehaul operation from 14 to 16 weeks.

PM Checks. The routing and securing of the grease lines from the pumping system to the individual lube points are critical. Check that the lines are not loose and flopping around; route them away from areas where the line could be pinched or cut. Also include the system in PM checks. Technicians should cycle the automatic lube system each time a tractor is serviced. The objective is to verify that the solenoids are functioning and to check if the proper amount of grease is being pumped into a component. If not, the controller time cycle can be adjusted. Being able to adjust individual grease amounts is important because some components require more grease than others. Both manual and automatic chassis lubricating systems are, in simplest terms, hydraulic systems for pumping grease. Some automatic systems use standard shop greases rated #1 or #2 by the NLGI; others require liquid greases with NLGI ratings of 000 and 00. These greases tend to stay fluid over a wide range of operating temperatures. Using these two ratings of grease, one manufacturer reports that its systems are dependable in temperatures ranging from 225° to 100°F (232° to 138°C).

Automatic chassis lube systems can be added to older trucks that do not have it. When retrofitting a system, there are several installation tips to keep in mind:

In tilt cab vehicles, do not tilt the cab any further than the truck builder recommends.

Metering valves, which distribute lubricant, should be placed alongside the vehicle, and if on the ground, away from any dirt or other contamination.

All lines or tubing should be fixed a sufficient distance from any heat sources (exhaust components, for example).

Clip/trim all tubing well to avoid chafing and abrasion.

Take care when drilling to avoid damage to the compressed air or electrical lines.

It is important to make the system a part of the truck, but separate from the air and brake lines, and chassis wiring.

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