Manitowoc 2250 Service Maintenance Manual

Reference Only
Manitowoc Published 07-19-16, Control # 249-01 2-7
2250 SERVICE/MAINTENANCE MANUAL HYDRAULIC AND AIR SYSTEMS
2
TIGHTENING THE HYDRAULIC
CONNECTIONS
General
1. Make sure the fittings and O-rings being used are the
proper size and style.
2. Flush the sealing surfaces with clean hydraulic oil to
remove any dirt.
3. Carefully inspect the threads and sealing surfaces for
nicks, gouges, and other damage. Do not use damaged
parts. They will leak.
4. Carefully inspect O-rings for cuts and other damage. Do
not use damaged O-rings. They will leak.
5. Lubricate O-rings when assembling them to fittings.
6. Be careful not to cut O-rings when assembling them to
fittings. Use a thimble as shown in Figure 2-4
when
assembling an O-ring over threads.
Pipe Thread Connection
1. Apply sealant (Loctite 92 or equivalent) to male threads,
never to female threads. Do not apply sealant to the first
two male threads.
2. Tighten fittings about 4-1/2 turns by hand and then 3
additional turns with a wrench.
Table 2-3. Pipe Thread Leakage
SAE Straight Thread Connection
See Figure 2-5 for the following.
This type of connection leaks most often because the jam
nut and washer are not backed up before assembly.
As shown in View A, when the jam nut and washer are not
backed up, there is not enough room for the O-ring when the
squeeze takes place and the washer cannot seat properly.
As shown in View B, the compressed rubber between the
washer and the spot face will cold flow out of compression,
causing the fitting to loosen and leak.
See Figure 2-6
for the following procedure.
Tighten SAE straight thread connections, as follows.
1. Back up the jam nut and washer to the end of the
smooth portion on the fitting (View A).
2. It is important to lubricate the O-ring with clean oil.
3. Thread the fitting into the port until the washer bottoms
against the spot face (View B).
NOTE: If an elbow is being used, back it out as necessary
to align it with the hose.
CAUTION
Hydraulic System Damage!
Debris can contaminate and damage the hydraulic
system.
Do not use FTE-fluorocarbon tape to seal threads. Pieces
of tape will enter the hydraulic system and cause damage.
Cause Cure
Fitting loose Tighten
Fitting too tight causing thread
distortion
Replace damaged parts
Fitting or port threads wrong size Use proper size threads
Threads dirty, galled, or nicked Clean or replace parts
FIGURE 2-4
S103
Plastic or Metal Thimble
Covering Threads
O-ring
Straight thread used instead of
tapered thread
Use proper type and size
thread
Female threads expanded from
heat
Tighten when hot
Cause Cure
FIGURE 2-5
The washer cannot seat properly
on the spot face. Compressed
rubber between the washer and
spot face will cold flow out of
compression, causing the fitting
to loosen and leak.
When the jam nut and washer
are not backed up, there is not
enough room for the O-ring
when the squeeze takes place.
S107
Jam Nut
O-ring
Washer
View A View B
FIGURE 2-6
Nut and washer backed up to end
of smooth portion on fitting.
S106
Jam Nut
Washer
O-ring
Spot Face
View A View B

Manitowoc 2250 Specifications

General

Brand	Manitowoc
Model	2250
Category	Construction Equipment
Language	English