NMC-WOLLARD MB-4 200-DF, Operation, Maintenance And Parts Manual

Page: 80 / 321

1. Tighten nut finger tight until it bottoms
the seat.
2. Mark a line lengthwise on the nut and ex-
tend it onto the adapter.
3. Using a wrench, rotate the nut to tighten.
Turn the nut the amount shown on the
following chart.
IMPORTANT! When tightening hydraulic fit-
tings, always use two wrenches to avoid
twisting hoses or lines.
Hose Size Rotate this no. of hex flats
4 2-1/2
5 2-1/2
6 2
8 2
10 1-1/2 – 2
12 1
16 3/4 – 1
20 3/4 – 1
24 ½ – 3/4
If joint leaks after proper tightening, discon-
nect hose and check for the following:
Problem Solution
Foreign particles in joint . . . . . . Clean
Cracked seats . . . . . . . . . . Replace
Seat mismatched . . . . Replace adapter
Nicks in seat . . . . . . . . . . . Replace
Excessive seat impression . . . . Replace
SAE 45° nuts . Use all SAE 37° flare parts
IMPORTANT! Leaks on this type of con-
nection won’t show until unit has been in
service for a few hours.
8.5.2 SAE Straight Thread O-Ring Seal
The O-ring fitting uses straight threads and
depends on an O-ring to prevent leaks.
IMPORTANT! If an O-ring seal leaks after
tightening, you will have to replace the
O-ring.
To install an O-ring seal:
The following procedure properly sets the
O-ring.
1. Back up jam nut and washer to
unthreaded portion of elbow adapter.
2. LUBRICATE the O-ring.
3. Thread elbow into port until washer bot-
toms onto spot face.
4. Position elbows by backing up adapter.
5. Tighten jam nut.
M200 MB4 Tow Tractor Manual No. 42975
PAGE 8-4
JULY 15, 2001
37 degree
flared nose
FIGURE 8-1. FLARED CONNECTION
(TYPICAL)
Back-up
washer
Locknut
O-ring
Spot face
FIGURE 8-2. SAE O-RING SEAL