By Ken Bannister, Contributing Editor
We must have at least a dozen different grease guns in our maintenance department. Some deliver more lubricant than others, yet our PMs call for a fixed amount of shots. Is this a problem?
There are no “standard” grease guns. While they may look similar, displacement and hydraulic pressure ratings vary from gun to gun. For example, a manufacturer may offer two lever-arm-actuated models: a low-pressure unit rated to deliver one fluid ounce of grease in seven strokes (shots) at a pressure of 1700 psi; and a similar-looking sister product rated to deliver one fluid ounce in 24 strokes at a staggering 15,000 psi! Note: Not all manufacturers state delivery or pressure on their guns or literature. You may need to ask for it.
If a PM calls for four shots of grease, the amount delivered will vary depending on the gun and setup. Over-lubrication, a huge problem in manual greasing, is magnified when a PM task states “grease as necessary,” which gives no clear direction on what’s required. In addition to being overfilled, the bearings could lose their seals under the resulting internal hydraulic pressure and allow contamination into the bearing cavity.
Ideally, a bearing cavity only needs filling to approximately 40% volume. If a single-point manual grease gun is your chosen delivery method, the following steps can help standardize your approach and reduce problems:
1. Implement a lubricating-grease consolidation program.
2. Collect and purge all grease guns in the plant and replace with a single design, preferably with a see-through barrel.
3. Perform a grease-gun displacement check by pumping 10 strokes or shots of grease into a large calibrated syringe, then read off the number of cubic centimeters or inches in volume and divide by 10 to get the actual volume displacement per shot or stroke.
4. Calculate bearing requirements and mark on a schematic attached to the machine or printed with the PM work order.
5. Optional: Color-tag individual grease points to denote grease type and mark the number of shots required per PM schedule.
6. Train grease-gun operators.
Good Luck! MT&AP
Dr. Lube, aka Contributing Editor Ken Bannister, is, among other things, a Lubrication Management Specialist and author of Lubrication for Industry and the Lubrication Section of the 28th Edition Machinery’s Handbook (both from Industrial Press). Email your lubrication checkup and training questions to: email@example.com; or telephone: (519) 469-9173.