New CAT® WEO Fittings Are Now Available for Certain Mini Hydraulic Excavators {0618, 3016, 4133, 4257, 4304, 5057, 7554} Caterpillar

Mini Hydraulic Excavator

306 (S/N: GW51-UP; 6G61-UP)

306.5 (S/N: GW61-UP)

307.5 (S/N: GW71-UP)

308 (S/N: GG81-UP; GK81-UP; GW81-UP; GX81-UP)

308.5 (S/N: GZ81-UP)

309 (S/N: GG91-UP)

310 (S/N: GWT1-UP)

Introduction

New CAT^® WEO fittings are now available for the machines listed above. The WEO fitting is designed to be connected and disconnected without the requirement for any special tools.

Do not perform any procedure in this Special Instruction until you have read the information and you understand the information.

Safety Section

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Do not operate or work on this product unless you have read and understood the instruction and warnings in the relevant Operation and Maintenance Manuals and relevant service literature. Failure to follow the instructions or heed the warnings could result in injury or death. Proper care is your responsibility.

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Failure to follow all safety guidelines prescribed in this document and by governing authorities and regulatory agencies may result in severe injury or death of personnel or machine damage.

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Personal injury or death can result from improper maintenance procedures. To avoid injury or death, follow the procedures exactly as stated below.

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Before servicing/performing maintenance on the machine, electrical power must be physically disconnected; battery plugs must be disconnected from the batteries, or the trailing cable must be unplugged, and warning tags and padlocks shall be applied by a certified electrician. Certified electricians shall perform or direct any electrical work, including any energized testing, repair work in controllers, motors, or other approved compartments, and shall insure that all compartments are properly closed and inspected prior to re-energization. All applicable lock out and tag out procedures must be followed.

WEO Fitting Working Principle

Illustration 1	g06415978
WEO fitting (A) Adapter (B) Nipple (C) Release ring (D) Assembly stop clip (E) Hose assembly (F) Dust seal

Connecting the WEO Fitting

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Illustration 2	g06415980
(C) Release ring (D) Assembly stop clip

1. Check that the assembly stop (D) is in place and the release ring (C) moves freely in the groove.
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   Illustration 3	g06415981
   (G) Pressure o-ring (H) Spring o-ring (J) Hooks

2. The male fitting is pushed into the coupler so that the hooks (J) in the coupler are pressed outwards.
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   Illustration 4	g06415982
   (D) Assembly stop clip (H) Spring o-ring (J) Hooks

3. The male fitting is pushed all the way in until the clip (D) touches the adapter. The spring o-ring (H) presses the hooks (J) inwards so that they grip the locking flange on the male fitting.
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   Illustration 5	g06415984
   Pulling backward to ensure the connection

4. Pull backwards to make sure the coupling is locked.

5. The coupling is now locked and sealed by the internal o-ring and backing ring.

Disconnecting the WEO Fitting

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Illustration 6	g06415985
(D) Assembly stop clip

1. Before disconnecting the WEO fitting, the stop clip (D) should be removed from the nipple. A simple flat-head screwdriver can be used to remove the clip.
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   Illustration 7	g06415986
   (C) Release ring (J) Hook

2. The nipple is pushed all the way into the adapter so that the release ring pushes the hooks (J). The hooks now sit on the release ring.
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   Illustration 8	g06415988
   (C) Release ring (J) Hook

3. As the male fitting is pulled out, the release ring (C) prevents the hooks (J) from locking so that the hooks then glide over the end of the nipple and allow disconnection.

Re-Connecting the WEO Fitting

Re-connecting the WEO fitting is the same as the initial connection.

Illustration 9	g06415991
(D) Assembly stop clip

Re-attach the clip (D) to the nipple.

Note: Risk of incorrect connection may occur if the assembly stop clip is missing during the connection.

WEO Adapter Service Caps and Plugs

Illustration 10	g06415992
(1) Male Plug

Illustration 11	g06415993
(2) Female Cap

As with any open hydraulic connection, service personnel should protect the connections from contamination. The WEO fitting is a special case as any contaminate particles that might become introduced into the adapter could cause the lock mechanism to malfunction.

Contamination can cause the lock mechanism to jam, creating a permanent, leak-free connection.

Contamination can also cause a failure to lock, this should be detected when the service personnel pulls back on the connection to ensure proper seating. If not detected here, it would blow out the coupling when the system is pressurized. Despite the failure, this is a benefit as it does not begin to leak a few hours after the service has been completed.

WEO Coupling Disconnect Methods

Generally, the WEO is disconnected by removing the assembly stop, pushing the coupling into the adapter to unlock, then pulling back to disconnect/retract the coupling.

Illustration 12	g06416017
(D) Assembly stop clip (K) Assembly stop shoulder (L) Adapter shoulder

Illustration 13	g06416018
(K) Assembly stop shoulder (L) Adapter shoulder (M) Assembly stop gap open

Illustration 14	g06416020
(K) Assembly stop shoulder (L) Adapter shoulder (N) Assembly stop gap closed

If the coupling moves freely but stops solidly in the home position when pulled back, then it has not unlocked. The most common cause of a coupling that seems as though it will not unlock is failure to push the coupling in far enough to unlock it. The assembly stop shoulder (K) must make contact with the adapter shoulder (L) to unlock properly. In situations where access is poor, or the hose assembly is in a bind, it may be tough to close this gap completely, even though it may look closed. In this situation, some force multiplication may be required.

WEO Coupling Disconnect Methods - Retraction

Illustration 15	g06416018
(K) Assembly stop shoulder (L) Adapter shoulder (M) Assembly stop gap open

At any point during retraction of the coupling from the adapter, if it seems too difficult to remove by hand, a prying force can be applied between the coupling and adapter shoulders with a flat head screw driver or other prying tool. This generates significantly more force than is possible by hand, and it should not require much force at all to retract the coupling by this method. If it starts to move but feels like a hard stop at the position shown in Illustration 15 (where only the assembly stop gap is visible) the connection is still locked. More force may be required to unlock it. This method can also be used to verify a connection has locked during re-connection.

WEO Coupling Force Multiplier Method - Percussion

Illustration 16	g06416022
(P) Wrench

Illustration 17	g06416025
(R) Hammer

Remove the assembly stop clip. Always try the standard push/pull by hand method before using more force. If that does not unlock the connection, push it up as far as you can and place the open end of a combination wrench around the hose at the base of the coupling crimp sleeve. The wrench face must be in contact with the crimp sleeve on both sides. Hit with a hammer (always wear safety glasses when using a hammer). The system is quite robust and can take a lot of force, but anything larger than a medium hit from a 32 oz ball peen hammer is probably over kill. Then, try pulling out the coupling again.

Repeat this step for two to three times. If this method does not unlock the coupling, it may be permanently locked. If it is determined to be permanently locked, the WEO adapter can be unscrewed from the mating adapter/component. This is a standard STOR joint. In this case, the adapter should be replaced.

WEO Coupling Force Multiplier Method - Prying

Illustration 18	g06416027
(S) Pry bar

Remove the assembly stop clip. Always try the standard push/pull by hand method before using more force. If that does not unlock the connection, push it up as far as you can. If there is a suitable site to act as fulcrum for prying, any suitable prying tool can be used to exert force against the bottom edge of the crimp sleeve (combination wrench, pry bar etc.,). Ensure that you are not prying against anything that is breakable.

Note: Depending on the length of the pry bar, large forces can be generated. Always wear safety glasses when using a pry bar.

Then, try pulling out the coupling again.

Repeat this step for two to three times. If this method does not unlock the coupling, it may be permanently locked. If it is determined to be permanently locked, the WEO adapter can be unscrewed from the mating adapter/component. This is a standard STOR joint. In this case, the adapter should be replaced.

WEO Coupling Force Multiplier Method - Ratchet Strap

Illustration 19	g06416028
(T) Ratchet strap

Remove the assembly stop clip. Always try the standard push/pull by hand method before using more force. If that does not unlock the connection, push it up as far as you can. If a suitable attachment point on the machine can be found, a ratchet strap can be used to apply additional force to the connection. Wrap one end of the strap around the hose at the base of the coupling. Locate a position to attach the other end of the strap. High forces will be generated, so ensure that the attachment is sturdy enough. Frames and brackets are preferred. Also, be sure that nothing fragile will be in the path of the strap when it becomes taught. The strap should align in the axial direction of the coupling within 20 degrees if possible. Tighten the ratchet strap, but do not use extraordinary effort to do so. Then release the strap and try to retract the coupling again.

Repeat this step for two to three times. If this method does not unlock the coupling, it may be permanently locked. If it is determined to be permanently locked, the WEO adapter can be unscrewed from the mating adapter/component. This is a standard STOR joint. In this case, the adapter should be replaced.

WEO Adapter Service Inspection

Illustration 20	g06416029
(J) Hooks

When a WEO connection is disconnected, the locking hooks in the female adapter should be inspected to make sure that none has dislodged or fallen out.

This is a rare occurrence, and would cause the locking mechanism to be non-functional. The hooks can only come out when there is no coupling connected as they are trapped in the lock gallery by the coupling.

Illustration 21	g06416033
Hooks location (U) All hooks present (V) Two hooks missing (W) All hooks missing

For inspection, a flashlight and a mirror can be used, depending on the fitting location and orientation. The Illustration 21 shows an example of a typical good adapter and adapter with hooks missing.

There are five individual locking hooks in each adapter. These hooks form a "ring" that is held in place by contact with each other and the tension applied by a spring o-ring. The edges of the hooks are clearly visible.

If one hook is removed, the loss of hook-to-hook contact removes all the tension and the remaining hooks will fall out easily.

Illustration 22	g06416034
Hooks intact, no o-ring visible (X) Adapter cartridge (Y) Adapter back shell

Illustration 23	g06416035
Hooks missing, blue o-ring visible (X) Adapter cartridge (Y) Adapter back shell

The spring o-ring that resides behind the hooks is blue in color to aid in visibility. If all hooks are present and in place, this blue o-ring should not be visible. Refer to Illustrations 22 and 23.

If a hook is missing, it must be accounted for. If a hook came out during the disconnect, it could fall back into the connection, enter the hydraulic system and cause damage to the pumps and motors.

It is unlikely that the coupling could be locked again with one ore more hooks missing and this would be easily detectable. But if a hook were out of place during the reconnect attempt, the hook could be pushed into they hydraulic system where it could cause damage to the pumps and motors if not recovered.

Once any missing hook(s) is accounted for, the adapter should be replaced with a new one.

Illustration 24	g06416037
(J) Hooks (X) Adapter cartridge (Y) Adapter back shell

While it is possible to disassemble an adapter (covered later under-removing a stuck connection), none of the parts inside are considered serviceable. It requires high precision equipment to reassemble the adapter correctly. If the adapter were not re-assembled correctly it can result in leaks, failure to lock and/or stuck connections.

Removing a Stuck WEO Connection

If it is determined that a WEO connection is permanently locked, then the hose can be removed by one of two methods:

Method 1

If the WEO adapter is straight, it can simply be unscrewed from the port, as WEO connections can rotate freely when fully locked. Once removed from the machine, try again to remove the adapter from the hose coupling by pushing down and then pulling back. If the adapter comes off, then it was not permanently locked and can be reused after it is inspected and cleaned and the STOR o-ring is replaced. If it does not come off, refer to"Method 2" for removing the WEO cartridge from the adapter.

Method 2

Illustration 25	g06416040
Unscrewing the coupling

Illustration 26	g06416043
(X) Adapter cartridge (Z) Thread locker (AA) Damaged release ring

Illustration 27	g06416048
(X) Adapter cartridge (Y) Adapter back shell

Illustration 28	g06416050
(AB) O-ring, NBR 70 (pressure seal) (AC) Support ring (AD) Washer, steel (AE) O-ring, NBR 50 (used as a spring) (AF) Catches, hardened steel (AG) Front part, steel (AH) Dust cap, plastic

If the WEO adapter is an angled fitting and cannot be unscrewed with the hose attached, it may be possible to remove the WEO cartridge from the adapter. If a suitable wrench is engaged on the hex of the cartridge, it can be unscrewed from the adapter body, taking the hose with it. The cartridge bits can be removed from the coupling. Things to aware of when attempting this removal:

• The cartridge hex is very short and the material is not hardened. It also uses a liberal coating of dry applied thread lock compound. Many attempts to remove these have resulted in round-off the hex. An appropriately sized pipe wrench seems to work best.

• The common cause of a permanent lock is damage to the plastic release ring on the coupling. Carefully inspect and replace this release ring if necessary. There should be no visible gap or pieces missing.

• In the event that the adapter is disassembled, it should be replaced with a new one. None of the parts inside are considered serviceable. It requires high precision equipment to reassemble the adapter correctly. If the adapter were not re-assembled correctly, it can result in leaks, failure to lock, and/or stuck connections.

WEO Coupling Service Inspection

Before connection of a new coupling, or re-connection of an old coupling, a visual inspection of the coupling is necessary to ensure it is in good condition and all soft parts (assembly stop, release ring, and dust seal) are present, installed properly and in good condition.

The coupling must be clean and free of debris before re-installation to avoid system contamination and possible lock malfunction.

The assembly stop must be present or the coupling will not lock when installed.

The release ring must be present and sitting properly in the groove.

Connecting without release ring will result in a permanently locked, leak-free connection.

Connecting with a damaged or out of place release ring could result in:

• Failure to insert completely and the coupling will not lock

• Permanently locked, leak-free connection

Illustration 29	g06416059
Release ring set in groove properly

Illustration 30	g06416066
Release ring partially out of groove

There is a clean split in the release ring that allows it to pass over the nose of the coupling for installation. This is normal, but typically the split would not be visible if the release ring is properly installed and in good condition. If the release ring stands noticeably out of the groove, it should be replaced. Refer to Illustrations 29 and 30.

The dust seal should be replaced if it appears damaged or worn. The coupling is fully functional without a dust seal but depending on environmental conditions and fitting orientation, this could result in contamination ingress that could bind the locking mechanism, resulting in a permanently locked, leak-free connection.

Illustration 31	g06416072
Uncleaned coupling

Illustration 32	g06416077
Coupling cleaned, release ring replaced and put back into service

Some corrosion or galling of the plating on a used coupling is not unusual. The coupling and soft parts can be cleaned with contact cleaner. Light corrosion can be removed with emery cloth or similar pad, once the soft parts are removed. More aggressive removals are not recommended as the body of the coupling is a sealing surface and deep scratches can cause a leak. If in doubt, replace the coupling.

Replaceable Soft Parts on the Male WEO Coupling

The parts listed in Table 3 can be ordered through your parts department. They are not required to be replaced unless they are found to be damaged or degraded during inspection.

WEO Coupling Connect and Re-connect

Align Coupling with Adapter

Illustration 33	g06416080
Proper alignment

Illustration 34	g06416082
Misalignment

• To reduce the assembly force, it is best to align the coupling and adapter before insertion

• If they are properly aligned, it should be fairly easy to fully insert

• If it seems too much force is required, then verify the alignment and try again

• A light coating of hydraulic oil can reduce friction, easing assembly forces, and is preferred

Insert Coupling

• Push the coupling into the adapter until the assembly stop bottoms out against the adapter

• You may feel a "click" sound when it connects, but not always

Check Connection

• Pull back on the hose to check that the locking hooks are seated

• A light prying tool (flat head screwdriver, putty knife, etc.,) can be used to check this as well

• Insert the prying tool between the assembly stop and the adapter and pry gently

• If the connection is not locked, it will come out.