Motor Bearing Lubrication
Irrigation Craft pump motors may require lubrication except for the Silent series pump stations which are water lubricated. First read the introduction and then the General Lubrication Guidelines.
Introduction - Why do Bearings Fail ?
Failed bearings are the largest single cause of motor failure. Bearings fail for many different reasons. The primary causes of bearing failure on pumps is:
² SEALED BEARINGS – Any attempt to lubricate a sealed bearing may destroy the bearing and the motor. Forced lubrication of a sealed bearing can deform and push the bearing seals into the rolling members of the bearing. Grease may also be forced through the bearing case seals into the motor itself.
² FAILURE TO LUBRICATE – The majority of bearing failures results from the lack of a regular and routine bearing lubrication plan, and the resulting mistake of simply not lubricating the bearing. Unless the bearing is sealed, all bearings require periodic lubrication.
² FAILURE TO REMOVE DRAIN PLUG - A very common lubrication error is failure to remove the drain plug when grease is injected into the bearing case through a zerk fitting. Failure to remove the drain plug causes a pressure build up in the bearing case which can deform the shields protecting the rolling members of the bearing and immediate bearing failure results. Failure to open the vent plug can also blow out seals in the bearing case and force grease into the motor itself.
² OVER LUBRICATION - Yes, you can over-lubricate a bearing. Over lubrication causes the rolling members of the bearing to slide instead of roll. Sliding balls or rollers generate excessive heat and scoring. Over lubrication can result from a mad man with a grease gun, but more likely just a zealous but uniformed maintenance technician.
² INCOMPATIBLE GREASE - Some greases are incompatible and should never be mixed. Discussions and opinions abound concerning what happens when incompatible greases are mixed. The safe choice is to avoid mixing. Always use the brand and type recommended by the original manufacturer. All standard Irrigation Craft pump stations require Exxon/Mobile Polyrex EM.
² WATER INTRUSION - Many Irrigation Craft pumps are located either outdoors or in locations with spraying water. Irrigation Craft standard products always contain TEFC motors. However TEFC motors are not to be considered "wash down" motors.
General Instructions
At the bottom of this page are links to the motor manufacturers. You can download the Maintenance Manuals for any motor used on Irrigation Craft standard pump stations. These Manuals contain valuable information on lubrication including schedules, types of greases, operating conditions, etc.
To set up your own lubrication procedure study the following information, and also read the Manual for your exact motor. Be sure first however that the bearings are shielded bearings and not sealed bearings. Read the note near the bottom of the page concerning sealed bearings.
- WHAT KIND OF GREASE ? - Determine what type of grease was originally installed in the bearing. You must use the same type of grease or risk incompatibility and rapid failure of the bearing. If you do not know what type of grease was used then consult the motor manufacturer, bearing manufacturer, or some other authority and select your own brand and type of grease. If you are changing the type of grease then remove the bearings and clean all the existing grease off the bearings. To assist you in finding a compatible grease we have listed the grease types used by the different manufacturers.
² BALDOR MOTORS – Exxon - Mobile Polyrex EM
² US ELECTRIC MOTORS – Exxon – Mobile Polyrex EM or Chevron SRI No. 2
² WEG MOTORS – Frames 143T up to 215T use Alvania R3 (Shell Oil). Frames 254T and larger use Esso Unirex N2. WEG states that Exxon-Mobile Polyrex EM is compatible.
- VENT PLUG ? - You must remove the vent plug when installing grease with a grease gun. You can now do one of two things regarding the bearing vent plug. Leave the plug installed and remove the plug each time you grease the bearing with a grease gun. The second and best method is to remove the vent plug and install a U shaped tube with the open end of the tube facing up and away from the ground. If the tube is exposed to rain or falling water then aim the tube open end parallel to the ground. Every time you grease the bearing with a grease gun the excess grease will flow through the vent tube and out. Wipe off the grease that exits the tube. The old grease left in the tube is a stiff and excellent plug to seal off the bearing from water and debris.
- FREQUENCY OF LUBRICATION ? - This is the most difficult part of any lubrication scheme. Since it is possible to over lubricate a bearing, you cannot play safe by simply injecting grease "all the time". Lubricating bearings with a grease gun is not the same as greasing the chassis on a car every time the car is in the garage. Below are a few helps to determine a lubrication schedule for your motors.
² Lubrication frequency must be determined by experience and knowledge. Lubrication schedules depend on the environment, motor usage, condition of the equipment, and changes in system operation.
² Examine the condition of the expelled grease. If the old grease is very dry and caked then increase the frequency of the lubrication schedule (shorter time between lubrications). If the old grease is similar to new grease then decrease the frequency.
Note On Sealed Bearings
Sealed bearings have a tightly sealed cover installed on both sides of the bearing. This cover seals the bearing internals from outside contamination and more importantly the cover seals in the grease or oil.
Any attempt to lubricate a sealed bearing will damage the bearing by deforming and forcing the seals into the balls/rollers. The grease may also be forced out of the bearing case into the motor windings, switches, and connections. The motor may fail because of this.
What is Grease ?
 | Grease consists of about 85% oil and 15% detergent or soap. |
| Oil is needed to lubricate bearings, but oil is hard to contain being a liquid. |
| The soap provides the essential desired quality needed, some stiffness to hold the lubricant in place. |
| The final product (grease) is a semi-solid which can lubricate. |
| Over time all the oil is depleted from the semi-solid leaving a thick waxy substance with little or no ability to lubricate. |
Motor Manufacturer's Operation Manuals
Below are links to the Manufacturer's web pages of the three brands of motors that are found on Irrigation Craft products. You can download the Installation and Maintenance Manual from their sites. These manuals contain the exact information you require concerning types of greases, lubrication intervals, etc.
