Installation Guide for Sprag Type Free-Wheel Clutches | GMN Bearing USA

Installation of Sprag Clutches

Proper lubrication with only qualified lubricants is the prerequisite for achievement of highest efficiency and long life of our high quality sprag clutches. Only with use of oil or grease lubricants specified in the tables below, GMN will warranty their Free-wheel Clutches and their trouble free function. Whenever possible, use only oil or oil mist lubrication rather than grease lubrication. Please contact our technical staff if operating temperatures are in the upper or lower temperature tolerance range, if the sprag clutch has to be mounted in vertical position or if there should be any other special conditions. Oil for oil mist lubrication please use hydraulic oil HM 10 or HM 32. The use of lubricants with additives that decrease the coefficient of friction, i.e. MoS22 or graphite is not possible.

Oil Type Operating Temperature Range
-15° C to 30°
C5° F to 86° F
15° C to 90° C59° F to 194° F 60° C to 120°
C140° F to 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

Oil lubricants described above - except hydraulic oil - are from the automotive sector. These lubricants can easily be obtained at automotive supply outlets and are excellent for the lubrication of our Freewheel Clutches. Lubricant qualification: HD-motor oil SAE 10 W or SAE 30 is equal to "API-Service SE or CC" and MIL-L-46152B".

Important: Oils shown in the table are only to be mixed with oils of the same qualification. That means ATF oil with ATF oil, HD-motor oil with HD-motor oil etc. If there is any change of oil from one qualification to the other, it is necessary to clean the Free-wheel Clutch and mating parts with cleaning or test benzine. Never use trichloroethylene or perchloroethylene.

The oil level should be in relation to the size of the Sprag Clutch. In normal installation position, not operating, one third of the clutch should be submerged in oil.

For oil mist lubrication systems we recommend ample clean oil, free of moisture, be sprayed directly onto clutches. Open or unsealed housings should be inspected frequently - at least daily - for proper lubrication level.

Our double sealed Free-wheel Clutches (series FND and FPD) are filled with an oil for operating temperature range 15° C to 90° C if not specially ordered.


Greases from different manufacturers may not be compatible. Consult with GMN for proper lubrication recommendations.

Please note: There is no universal grease for all service and operating conditions. The table below lists suitable grease types and characteristics for GMN Free-wheel Clutches.

Producer Grease Type Saponification Oil base Operating Temperature at GMN Free-Wheel Clutches 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

First two grease types to be used in standard applications.

The amount of grease should cover approximately 60% of the free volume in the clutch. Please take care for homogene dispersion of the grease all over the clutch.

GMN uses ball and roller bearing grease which is continually monitored for maximum quality and maximum clutch life. Sealed ball bearing clutches "RS" and "2RS" are shipped grease lubricated with grease type Isoflex LDS 18 Special A, if not specially ordered.

GMN can not endorse or guarantee the quality of lubricants, purchased by their customers to be used with GMN clutches. Last update of the qualifications: May 1999

Information about GMN Roller Ramp Clutches could be found here.

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