A pressure switch, pressure gauge or stroke counter can signal a blockage, as can a pump relief valve bypassing lubricant back to the reservoir. Before attempting to make repairs, inspect the entire system visually to look for crushed lines or improper component installation. Verify that each feeder divider outlet intended to discharge lubricant can do so and that no pipe plugs have been installed in an outlet designed to serve a bearing or feeder divider. If visual inspection proves inconclusive, follow these five steps to isolate the source of blockage.
Test individual feeder dividers for blockages by using a portable hand-operated testing unit equipped with a pressure gauge and filled with clean, filtered lubricating oil. Operate the testing unit at a pressure less than 3,000 psi. Using higher pressures invites the risk of blowing the seals in the block assembly. Connect the testing unit to the lines of the master feeder and slowly operate the unit (see Figure 1). If the system won't operate freely at a pressure below 2,000 psi, go to step two. If, however, it operates freely, the source of the problem is either the lubricant supply pump or a blockage between the supply pump and the manifold.
Figure 1. Connect the testing unit to the lines of the master feeder and operate it slowly.
With the portable tester still connected, remove each outlet plug, one at a time, and attempt to operate the manual pump at no more than 2,000 psi. If the pressure drops and the master feeder cycles freely, the blockage is downstream of the outlet being tested.
When an outlet plug that corresponds to a blocked area is removed, a small amount of trapped lubricant is released as the inlet pressure at the divider valve drops. If all outlet plugs have been removed and the master feeder still won't cycle, the blockage is located in the master feeder divider valve. Disassemble and clean the valve block.
Figure 2. Remove the alternate outlet plugs in the secondary divider valve assembly.
Attach the manual pump to the alternate outlet on the master divider valve that is common to the blocked area. Disconnect the supply line at the secondary inlet fitting and slowly operate the manual pump.
Proceed downstream to the secondary divider valve assembly and remove the alternate outlet plugs (see Figure 2). If the pump now moves lubricant freely through each alternate outlet, you know the blockage can't be in the supply line or the divider valve. In that case, go to step four.
If, on the other hand, lubricant isn't discharged through the open alternate outlets in the secondary divider valve, the blockage must be in this divider valve or its supply line. If fluid discharges through the supply line, the blockage is in the secondary divider valve assembly. Go to step five.
Connect the pump to each alternate outlet in the secondary divider valve assembly in turn and slowly operate the pump (see Figure 3). If it's possible to achieve a high pressure, you've located the blockage. Look for crushed lines, tight bearings, improperly drilled fittings and lube inlet ports. A divider feeder valve with a blockage or malfunction must be disassembled, repaired and reassembled.
At a minimum, replacement parts must meet the manufacturer's specifications. On the other hand, the best way to avoid having to go through this exercise again is by using only OEM parts. Establish a parts catalog based on OEM parts bulletins and maintain an inventory of parts frequently replaced. This saves time when the lubrication system needs servicing.
Figure 3. Connect the pump to each alternate outlet in the secondary divider valve assembly in turn.
Disassemble, repair and reassemble the divider valve. The following is the recommended procedure for the disassembly and reassembly of divider valves.
Before removing a divider valve from the system, make a sketch and note the arrangement of the divider block. You also can use a digital camera to record the exact configuration. Indicate the following items on the sketch to ensure the divider block is reassembled and installed correctly:
Arrangement of intermediate sections.
Location and size of performance indicators.
Location and type of cross-port plates or blocks.
Location of singling plates or blocks.
Location of doubling plates or use of short-long plugs.
Clean the external surfaces of the valve block to remove dirt and excess lubricant. Inspect the exterior of the block to check for cracks or deformities.
Because dirt and other contaminants are the worst enemies of any lubricating equipment, work in the cleanest environment possible. Remove the tie rod nuts. Begin a thorough visual examination of the internal valve components, looking for damaged or blown gaskets between each section. Using a wire probe, check internal passageways for blockage. Also, inspect the gasket surfaces for defects.
Examine the inlet and end sections of the valve manifold. Inspect each port and drilled passageway. Make sure they are clean and open.
Disassemble each valve section one at a time to prevent mixing parts among sections. Using a brass rod and hand pressure only, carefully remove the valve piston from the valve section. Never put sharp or hard metal objects within the piston bore.
Clean the sections in a suitable solvent to remove all traces of lubricant. Use compressed air to blow out and dry all ports thoroughly. Examine the pistons and piston bores for scratches, score marks and other damage.
Reassemble the valve section. Don't interchange pistons or attempt to refit pistons. Valve bores are honed to achieve a perfectly matched fit with a particular piston. If either the piston or bore is damaged, install a new valve section.
Referring to the sketch made before disassembly, reassemble the sections in the correct stacking positions using new intermediate gaskets. Torque the divider block fasteners to the specified values shown in Table 1. Finally, bench-test the unit before reinstalling it.
Routine testing for blockage, and necessary repairs to remedy it, ensures that proper lubrication keeps your equipment running smoothly.
Anne Spano is director of customer training at Applied Industrial Technologies, Cleveland. Contact her at (216) 426-4406.
Figures: Applied Industrial Technologies