GUID-03108AC9-D116-472B-8878-816A93A7CD2D-high.jpg [High]
Fig. 47
Straight thread fittings
The straight thread hydraulic fittings require accurate tightening. Overtightening of the hydraulic fittings will
damage the sealing surfaces and will require the replacement of the damaged parts.
Correct initial tightening depends on the mating parts to be connected. Continue as follows:
An adapter fitting (37° flare) connected to a double flare tube assembly. Tighten the fitting finger tight and
wrench the fitting 1/2 turn (for single flare, 1/4 turn).
An adapter fitting (37° flare) connected to a hose. Tighten the fitting finger tight and wrench 1/4 turn.
An O-ring adapter fitting connected to a solid port: Tighten the fitting until the backup washer contacts the
face of the boss after aligning the fitting.
Tighten after initial tightening, as in service work: Tighten both the tube and the hose connections finger
tight and wrench 1/4 turn. O-ring fittings must be tightened as for initial assembly.
JIC SWIVEL NUTS (37° SEAT). The maximum recommended torque values for JIC (37° seat) swivel nuts,
either swaged or brazed type, follow. Swivel nuts usually withstand this torque for a minimum of 15
repeated assemblies.
The torque required to seal female swivel fittings or hose couplings to a male connector depends on many
variables. Fluid medium, pressure, surface finish, and so on are some of these variables. Use the following
values only as a guide for the torque maximum values to apply to the fittings.
DASH SIZE
TUBE O. D. (REF)
TORQUE MAX
Nm
lbf in
lbf ft
-4
1/4
12
110
9
-5
5/16
20
180
15
-6
3/8
27
240
20
-8
1/2
40
360
30
-10
5/8
54
480
40
-12
3/4
95
840
70
-14
7/8
110
980
80
-16
1
120
1080
90
-20
1 1/4
160
1440
120
-24
1 1/2
180
1575
130
4
1. General
Rubber Track Tractor
1-47
79036614D
