Relief Fittings
Used on gearbox housings and bearings.
The fittings open at pre-determined pressures as shown.
These fittings can be used with either grease or oil.

Part # Description Style
Pressure
Height
Shank
Hex
Alemite #
Lincoln #
MB317400 1/8" Npt w/Plunger Top Vent
1/4-1 psi
1/2"
19/64"
7/16"
317400
MB47200 1/8" Npt w/Plunger Top Vent
1-5 psi
1/2"
19/64"
7/16"
47200
MB47640 1/8" Npt w/Plunger Top Vent
7-1/2-15 psi
1/2"
19/64"
7/16"
47640
MB323060 1/8" Npt w/Plunger Top Vent
15-25 psi
1/2"
19/64"
7/16"
323060
MB47100 1/8" Npt w/Plunger Top Vent
45-80 psi
1/2"
19/64"
7/16"
47100
MB50500 1/8" Npt w/Plunger Top Vent
400-650 psi
1/2"
19/64"
7/16"
50500
MB321839 3/8" Drive w/Plunger Top Vent
1-5 psi
1/2"
19/64"
7/16"
321839
MB338382 1/8" Npt Leak proof  
80-140 psi
9/16"
11/32"
7/16"
338382
MB5677 1/8" Npt W/Ball Side Vent
7/16"
9/32"
7/16"
5677
MB5678 1/8" Npt W/Ball Side Vent
7-1/2-15 psi
7/16"
9/32"
7/16"
5678
MB5679 1/8" Npt W/Ball Side Vent
15-25 psi
7/16"
9/32"
7/16"
5679
MB5680 1/8" Npt W/Ball Side Vent
45-80 psi
7/16"
9/32"
7/16"
5680
MB317400-4 1/4" Npt Top Vent
1/4-1 psi
31/32"
31/64"
9/16"
MB47200-4 1/4" Npt Top Vent
1-5 psi
31/32"
31/64"
9/16"
MB47640-4 1/4" Npt Top Vent
7-1/2-15 psi
31/32"
31/64"
9/16"
MB323060-4 1/4" Npt Top Vent
15-25 psi
31/32"
31/64"
9/16"
MB47100-4 1/4" Npt Top Vent
45-80 psi
31/32"
31/64"
9/16"
MB50500 1/4" Npt Top Vent
400-650 psi
31/32"
31/64"
9/16"
MB317400-6 3/8" Npt Top Vent
1/4-1 psi
1"
15/32"
11/16"
MB47200-6 3/8" Npt Top Vent
1-5 psi
1"
15/32"
11/16"
MB47640 3/8" Npt Top Vent
7-1/2-15 psi
1"
15/32"
11/16"
MB323060-6 3/8" Npt Top Vent
15-25 psi
1"
15/32"
11/16"
MB47100-6 3/8" Npt Top Vent
45-80 psi
1"
15/32"
11/16"
MB50500-6 3/8" Npt Top Vent
400-650 psi
1"
15/32"
11/16"
MB317400-8 1/2" Npt Top Vent
1/4-1 psi
19/64"
9/16"
13/16"
MB47200-8 1/2" Npt Top Vent
1-5 psi
19/64"
9/16"
13/16"
MB47640-8 1/2" Npt Top Vent
7-1/2-15 psi
19/64"
9/16"
13/16"
MB323060-8 1/2" Npt Top Vent
15-25 psi
19/64"
9/16"
13/16"
MB47100-8 1/2" Npt Top Vent
45-80 psi
19/64"
9/16"
13/16"
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