Proper lubrication with quality lubricants will ensure your GMN sprag clutch is operating at the highest efficiency and long life span.
When the sprags are in the freewheeling state, there is sliding contact between the sprags and the shaft and housing surfaces. So, there must be a film of oil to protect against metal-to-metal contact. If the oil film isn’t present or is not adequate, then excessive wear and premature failure would occur. However, too much lubrication can also cause the sprags to not engage properly or it can generate too much drag.
For oil bath systems, GMN recommends 1/3rd of the sprag clutch height is submerged.
For greased clutches, GMN recommends 30-60% of the available volume to be greased.
Some oils or greases, especially in engine or gear box applications, can have anti-friction (or EP) additives in the lubrication. While these additives are great for gears and other components, they hinder the performance of the sprags and can prevent them from engaging. These additives are designed to make sure a film of oil remains in place between the metal components no matter how much pressure is applied.
However, the sprags must be able to push through the oil layer and act directly against the metal shaft and housing when engaging or they will slip. For this reason, lubrication without these additives is required for GMN clutches.
GMN Standard Clutch Lubrication
All GMN’s sealed clutches come lubricated for life with grease in the Ball Bearing units and oil in the Complete units. GMN can supply open clutches pre-greased, andstandard manufacturing lead times will apply.
The tables below show a few suggestions for both oil and grease lubrication that we’ve tested and proved to be successful. If you’d like another lubrication that’s not listed below, contact us so we can make sure it’s compatible and won’t result in failure.
|OIL TYPE||OPERATING TEMPERATURE RANGE|
| -15°C – 30°C|
(5°F – 86°F)
|15°C – 90°C|
(59°F – 194°F)
|60°C – 120°C |
(140°F – 248°F)
|Hydraulic Oil||Hydraulic Oil HM 10||Hydraulic Oil HM 32 D||Hydraulic Oil HM 100|
|Motor Oil||HD-Motor Oil SAE 10 WATF-DEXRON III||HD-Motor Oil SAE 30|
Motor oil lubricant is the type you find in the automotive section. Please note: HD-motor oil SAE 10 W or SAE 30 is equal to API-Service SE or CC or MIL-L-46152B.
Important: Only mix oils with the same type of material and components. For example, ATF oil should only be mixed with ATF oil and HD-motor oil should only be mixed with other HD-motor oil, etc. If there’s ever an oil brand change it’s necessary to clean the Sprag Clutch and all its mating parts. Never use trichloroethylene or perchloroethylene to clean any components.
Oil levels should be in relation to the size of the sprag clutch and one-third of the clutch (in normal position, not operating) should be submerged in oil.
Clean oil, free of moisture, should be sprayed directly onto clutches for oil mist lubrication systems. Daily inspection of open or unsealed housings will ensure proper lubrication levels.
For operating temperatures between 15°C to 90°C, our double-sealed sprag clutch series, FND and FPD, are filled with standard oil (unless you put a special request in with your order). Other lubrication types are available, contact us for more details.
|-65 to 100º C||-35 to 160º C||15 to 90º C|
Isoflex PDP 38
Turmofluid SF 48
GH 6 oils
Tellus S2 MA 32
|Oil Type||Diester oil based||Polygl.oil based||Mineral oil|
|Characteristics||Synthetic long-term oils||Synthetic transmission|
and high-temp oils
Some types of grease won’t work with our sprag clutch line, especially if they contain additives.
For example, lubrication additives like extra pressure (EP) additives for transmission or gearbox applications may prevent the the sprag clutch from working properly. Greases from different manufacturers may not be compatible. Contact us with any questions or for proper lubrication recommendations.
Please note: There is no universal grease for all service and operating conditions. The table below lists tested and approved grease types for our sprag clutch products.
|PRODUCER||GREASE TYPE||SAPONIFICATION||OIL BASE||SPRAG CLUTCH OPERATING TEMPERATURE||CHARACTERISTICS|
|Klüber Lubrication||ISOFLEX LDS18 Special A||Lithium||Ester/Mineral||-30° C … 130° C|
-22° F … 266° F
|Deep temperature and long-term grease with high resistance to aging and corrosion.|
|Shell||Alvania RS||Lithium||Mineral||-10° C …120° C|
14° F … 248° F
|Long term grease with high resistance to aging and corrosion.|
|Klüber Lubrication||Bio BM72-50||Polyurea||Ester||-20° C …120° C|
-4° F … 248° F
|Biological grease especially for overrunning and backstopping|
|Klüber Lubrication||Synth HB72-102||Polyurea||Ester||-40° C …180° C-40|
° F … 356° F
|Synthetic grease especially for overrunning and backstopping|
The correct amount of grease should cover approximately 60% of the free volume in and around the sprags of the clutch.
|Operating Temperature||-50 to 120º C||-40 to 180º C||-40 to 200º C||-40 to 260º C|
LDS 18 Special A
Highspeed L 252
GHY / HQ 72-102
NBI 300 P
GHY / HQ 72-102
|Base Oil||Mineral oil|
|Diester oil||Perfluropolyether oil|
|Thickener||Lithium soap||Polyurea||Polyurea, PTFE||Polyurea|
|Characteristics||Dynamically light long-term lub. grease||Synthetic long-term lub. grease||High temperature long-term lub. grease||High temperature long-term lub. grease|
Best Practices for Applying Grease
We recommend letting our technicians grease the clutch for you but if this goes against your standard operating procedure we understand. In that case, here are our suggestions for applying grease yourself:
- Utilize a clean room
- Use gloves
- Use lint-free wipes
- Change the air filter often in the room you are using
When we grease sprag clutches, we commonly use ball and roller bearing grease because it’s continually monitored for maximum quality and maximum clutch life. Sealed ball bearing clutches “RS” and “2RS” are shipped grease lubricated with standard grease Isoflex LDS 18 Special A.
Please note: If you decide to purchase your own grease or oil lubricant, we can’t endorse or guarantee the quality of our sprag clutch line. We recommend allowing our technicians to lubricate the GMN sprag clutch.
Interested in GMN Sprag Clutches?
Check out our Sprag Clutch Guide resources below for more information.