Removing the Clutch Assembly
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| Illustration 1 | g00500486 |
(A) 139-5635 Air Clutch (B) 150-9166 Clutch (1) Coupling hub (2) Spacer (split ring) (3) Drum (4) Element assembly (5) Adapter for the element (6) Air tubes (7) Hub (8) Bearing support (9) Gearbox shaft (10) Adapter ring | |
- Connect a strap to the element assembly. Apply tension that is sufficient to support the entire weight of the assembly.
- For reassembly, mark the following components:
- Coupling hub (1) and spacer (2) (if equipped) to drum (3)
- Element assembly (4) , adapter for the element (5) , and adapter ring (10) (if equipped) to gearbox hub (7)
- Coupling hub (1) and spacer (2) (if equipped) to drum (3)
- Disconnect air tubes (6) from the adapter for the element (5) and gearbox shaft (9) .
If the clutch has roll pins for orientation, remove only the roll pins from the components that are being disassembled.
Remove the bolts that connect the adapter for the element (5) and hub (7) . If the clutch has an adapter ring, remove the bolts that connect adapter ring (10) to the adapter for the element (5) .
Remove the clutch assembly.
- Lay the clutch assembly on a clean, level surface. Place the flange for the air tubes upward. Disconnect element assembly (4) from the adapter for the element (5) .
Do not disconnect the adapter for the element (5) , bearing support (8) , and drum (3) . Lift these connected parts from element assembly (4) .
Disassembling the Dual Elements
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| Illustration 2 | g00500488 |
Dual element (1) Flange for air tubes (2) Coupling (3) Long air tube (4) Fastener | |
Perform this procedure with the dual elements on a clean, level work surface.
- Loosen coupling (3) .
- Remove the fasteners (4) that connect the elements.
- Separate the elements.
Inspecting the Friction Shoes
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| Illustration 3 | g00500490 |
Element (1) Elbow (air) (2) Air actuating tube (3) Friction shoe (4) Pin (5) Lockwire | |
| NOTICE |
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Operation with friction material that is less than the minimum allowable thickness will result in damage to the drum. |
Inspect the friction shoes for wear of the linings. Linings with wear that is uneven may indicate a worn drum or misalignment.
Measure the thickness of the linings. If the linings are worn to the minimum allowable thickness, the complete set of linings must be replaced. The minimum allowable thickness of the linings depends on the element that is used.
- For the 4C-B200 Element , the minimum allowable thickness is 0.8 mm (.032 inch) .
- For all other elements, the minimum allowable thickness is 1.5 mm (.06 inch) .
Inspect the friction shoes and the drum for oil and grease contamination. Contamination will reduce the torque of the clutch.
| NOTICE |
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Do not use a solvent for removing oil or grease without removing the element. Spraying a solvent into an installed element can cause a fire from the heat that is generated. Remove the element before cleaning. |
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Do not use compressed air for cleaning dust from between the friction shoes even if the material does not contain asbestos. The dust may irritate the respiratory system. Use a vacuum for removing the dust. |
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If oil or grease is detected, disassemble the element. Remove dust that is between the friction shoes with a vacuum. Clean the internal parts of the element. A light contamination of oil or grease may be removed with a solvent. Replace the lining if either of these conditions are found:
- The lining is saturated with oil and/or grease.
- The lining is charred from excessive heat.
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Do not attempt to sand material that contains asbestos. Use the appropriate precautions for working with asbestos. |
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To check the lining for asbestos, clean the edge of the lining. The lining contains asbestos if the following composition is found: green stripe, yellow stripe and brass flakes. Carefully remove the linings. Dispose of the linings according to local regulations.
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Use caution in order to avoid breathing dust that may be generated from handling any friction material, regardless of whether or not the material contains asbestos. If the dust is inhaled, the dust can be hazardous to you health. Wear a proper protective breathing device when handling friction material. |
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Inspect the surface of the friction shoes. If the linings are glazed, the glazing may be removed by lightly sanding the lining. Do not sand the lining if the lining contains asbestos.
Replacing the Friction Shoes
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| Illustration 4 | g00500491 |
(1) Lockwire (2) Scallop (3) Pins | |
- Remove lockwire (1) . Discard the lockwire.
- Remove pins (3) .
- Remove the friction shoe from the element. Discard the friction shoe.
- Place the new friction shoe in position. Insert the pins. Ensure that pinhead (5) is located on the side with the flange for the air tubes.
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| Illustration 5 | g00504663 |
(4) Flange for the air tubes (5) Pinhead | |
- To secure the friction shoe, insert lockwire (1) through the holes of two pins. Ensure that the scallop (2) points away from the friction material (Illustration 4 ). Center the lockwire so that equal lengths of wire extend from each pin. Bend the ends of the wire toward the friction material.
Measuring the Diameter of the Drum
Note: Heat may cause minor checking of the drum. This may be removed by machining the outer diameter of the drum.
If the drum has been exposed to excessive heat, the open end of the drum may flare outward. If this occurs, the drum may not appear to be worn. Therefore, it is important to measure the diameter of the drum.
Measure the outer diameter of the drum at several locations. Compare the measurements to the information that is listed in Table 1.
| Wear Limits for the Drum | |
| Element (1) | Maximum Allowable Wear Limit |
| 4CB200 through 14CB400 | 2.3 mm (.09 inch) |
| 16CB500 through 24CB500 | 3 mm (.12 inch) |
| 26CB525 through 40CB525 | 4.8 mm (.19 inch) |
| 45CB525 | 6.4 mm (.25 inch) |
| ( 1 ) | The numbers that precede "CB" represent the original diameter of the drum in inches. |
To calculate the minimum allowable diameter, subtract the maximum allowable wear limit from the original diameter of the drum. Table 1 is an example for using the information that is listed in Table 2.
| Example for Calculating the Minimum Allowable Diameter of the Drum | |
| Original Diameter of Element 10CB300 | 254 mm (10 inch) |
| Subtract the maximum allowable wear limit. | 2.3 mm (.09 inch) |
| The difference is the minimum allowable diameter. | 251.7 mm (9.91 inch) |
For the example in Table 2, replace the drum if the diameter is less than 251.7 mm (9.91 inch) .
Inspecting the Air Actuating Tube
The air actuating tube is bonded to the outer rim of the element. The tube is constructed of synthetic rubber and cord. When air pressure is applied into the tube, the tube inflates. This forces the friction shoes against the drum in order to engage the clutch.
The air actuating tube can be damaged by heat. Inspect the tube for damage. Replace the element if any of the following conditions are found:
- The tube is hard.
- The tube is charred.
- The tube is blistered.
- The ply of the tube is separated.
Adjusting the Engagement of the Clutch
The clutch element will automatically compensate for wear of the linings and the drum.
Note: To enable rapid disengagement of the clutch, the flow of air from the clutch must not be restricted.
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| Illustration 6 | g00519969 |
Top view of the air control for the clutch (1) Valve (2) Solenoid | |
The engagement of the clutch can be regulated by valve (1) that controls the air flow to the clutch. The valve is installed in the line that supplies air to the clutch. The rate of clutch engagement can be adjusted by regulating the air flow to the clutch.
The gauge for the air pressure to the clutch should rise to full pressure within two seconds after solenoid (2) is actuated.
Note: The torque that is developed depends on the speed of rotation and the air pressure that is applied. Limiting of the air pressure will limit the torque. This will help to prevent overloading. The valve that controls the air flow to the clutch does not regulate the air supply pressure. The air supply pressure must always be adequate in order to transmit the maximum torque that may be required.