GOMACO World Index --- GOMACO World 33.2 - September 2005


Stop Unexpected Trimming Problems
Tips To Create Your Own Detailed Maintenance Program


Emergency Stop buttons

Check your Emergency Stop buttons

There’s more to trimmer maintenance than checking oil levels, greasing a few grease fittings and filling the machine with fuel.

From a safety standpoint, perhaps one of the most important items to check on a daily basis is the operation of the Emergency Stop (E-Stop) system. It is important to make certain that depressing any E-Stop button on the machine will stop all systems. If depressing a button fails to stop the various systems, the problem should be corrected before operating the machine.

Another important safety item to check daily is the conveyor lift/swing alarm system. Make certain that when the conveyor is raised or lowered, or swung left or right, that the warning alarm sounds. If the alarm does not sound, correct the malfunction before operating the machine. Also make certain that the backup alarm sounds whenever the travel system is in the reverse mode.

Another important item to check is the condition of the trimmer teeth and their relationship to the trimmer moldboard. Any teeth that are worn or damaged must be replaced before the tooth holder is damaged. The trimmerwheel should be adjusted so that the teeth are cutting the grade 0.25 to 0.375 in. (6 to 10 mm) below the moldboard.

Hydraulic filter changes should be made at the intervals listed in the maintenance portion of the owner’s manual. Changing the filters at the proper intervals will keep the oil clean and the systems working at peak performance. On newer machines, additional filters have been added for the conveyor pumps. Make certain when replacing filters, that the old seal ring is removed with the filter. It is recommended to have a sample of the hydraulic oil analyzed to determine if it needs replacing. Always make certain to dispose of the filters and oil according to local regulations.

Check the level of the gear lube in the various gear boxes on the machine. If the level is low, fill the gearbox to the proper level with EP-90 gear lube. If hydraulic oil is present in the gearbox, it indicates that the seal on the motor or pump(s) may have failed. It will be necessary to replace or repair the failed component. The oil in the gear boxes should be changed after the first 50 to 100 hours on a new machine and then annually after that. Always make certain to dispose of the oil according to local regulations.

Air filter maintenance is of utmost importance to maintaining a healthy engine. If the air filter is clogged, fuel economy will suffer, along with a loss of power. When replacing the air filter, don't overlook the safety element. If there is any indication that the main filter element has been damaged, the safety element may need to be replaced as well.

Check all of the connections between the air filter and the engine to make certain that they are tight. Make certain that none of the hoses or tubing are rubbing against any obstacle that could create a hole for dirt to enter the system.

Check the condition of the various hydraulic systems. The best method used to check the condition of the various hydraulic systems is by connecting a flow meter into the circuit. By using a flow meter, the condition of the pump can be checked in addition to checking the pressure relief adjustments. With the flow meter connected to the system, run the engine at maximum speed (hydraulic oil should be warm). Activate the system and note the flow on the meter with no pressure restriction. Gradually close the valve on the flow meter to increase the pressure in the system.

Continue to increase the pressure until the pressure gauge is at approximately 80 percent of the relief pressure setting. Note the flow on the meter. It should be at least 90 percent of the no pressure flow. If the flow drops lower than 90 percent, the pump is defective and should be repaired or replaced. If the flow is 90 percent or greater, the pump is in usable condition.

If the pump flow is good, continue to close the valve on the flow meter until the pressure relief valve for the system opens. Note the pressure reading on the appropriate gauge. If the pressure is incorrect, turn the pressure relief valve adjustment screw in or out as necessary.

Example: If the pressure relief valve is set at 2150 psi (148 bar) and the no pressure flow is 22 gpm (83.3 lpm), increase the pressure to 1720 psi (118 bar) (2150 psi x 80 percent; 148 bar x 80 percent). The flow should be at least 19.8 gpm (75 lpm) (22 gpm x 90 percent; 83.3 lpm x 90 percent).



trimmer teeth

Check for worn trimmer teeth



hydraulic filters

Change hydraulic filters



gear lube

Check the level of the gear lube


air filters

Maintain the air filters




The electrical systems should be thoroughly checked to eliminate any problems. Visually inspect the frame wiring and repair or replace any that is damaged. Inspect the bulkhead connectors and plugs for moisture or corrosion and clean using a contact cleaner.

Connect the sensors and place the control system in automatic. Move the grade sensor wands and notice if the machine moves up and down with the sensor. Slowly start the machine moving in the forward direction. Move the steering sensor wand and notice if the machine turns left and right. If the grade or steering system will not respond as described, then there is a fault in the system.

If the machine will not travel in a straight line when the steering sensor, or manual steer knob, is in the center position, it may be necessary to adjust the pump stroke controller or the EDC drive from the control system. Re-adjust the slope sensor following the instructions in the owner/operator manual. Check the operation of the conveyor controls. It may be necessary to adjust the HAC cards on earlier machines, or the threshold settings on current machine. Make certain that the battery cables and posts are clean and tight and that the battery is fully charged (heart of electrical system).

It is also recommended to check the condition of mechanical components such as bearings, chains and belts. Check the condition of the various bearings and bushings on the machine and replace them as necessary. Check the condition of the belts on the front of the engine and replace any that are damaged. Make certain that the belts are properly tensioned.

Check the conveyor belt and replace or repair it as necessary. Run the conveyor belt and make certain that it is properly tensioned and trained. Check and repair the belt cleaners as required. Check and repair or replace any components on the tracks that are damaged or worn. Check all drive chains and sprockets for wear and tension the chain as required.

Check for any oil leaks and repair them. Clean the machine of all concrete, oil and dirt. Replace any decals that are worn or damaged beyond recognition. If the machine has an excessive amount of concrete build-up, or is faded or rusty, it may be necessary to clean (sand blast) the machine and repaint it.

Note: If any of the machine systems require adjustment, refer to the appropriate machine owner/ operator’s manual for complete instructions. There are several other maintenance items that need to be preformed in addition to those listed here.

Performing timely maintenance will help eliminate unexpected problems from rearing their ugly heads at the most inopportune times (such as in the middle of trimming). No one wants to experience unexpected problems and a detailed maintenance schedule will help to assure that most of those problems will not occur.



hydraulic systems

Check the condition of the hydraulic systems



electrical systems

Check the electrical systems



mechanical components

Check the condition of mechanical components






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