6 x 3 And 8 x 3 Type HM Brakes | |
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Use pipe wrench to unscrew and remove spring barrel and parking spring assembly (30-38). (See drawing below.) The remaining actuator on the brake can now be removed in the same manner as the type H actuator. To service the cup, seal and retaining spring, disassemble the spring barrel and parking spring assembly (30-38). Remove retaining screw (36). This releases push rod and seal (30-31), as well as piston (32), cup (33) and retaining spring (34). The spring barrel and parking spring (37-38) are not serviceable and normally need not be further disassembled. If disassembly is attempted, note that the parking spring is preloaded to about 200 pounds force. The use of an arbor press is essential. If the cylinder walls are scratched or corroded, replace the complete J3054 HM Actuator. Otherwise wash all parts in denatured isopropyl alcohol. Discard items 21, 27, 28, 30 and 33 and use new parts from J73919 Repair Kit. Coat all parts with Super Heavy Duty Brake Fluid and reassemble in reverse disassembly order. To insure proper seal in park release cylinder, be sure the retaining screw (36) is tight. Note that the park release cylinder must be kept released when the reassembled brake is readjusted. |
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AND ANTI-DRAG SERVICE Brake lining must be replaced when it has worn to less than 3/16" thickness. To reline type HM brakes, the brake arms must be opened by removing clamp nut (16), adjusting nut (15) and hinge pin (11). The brake lining and lining bolt assemblies may then be replaced in the same way as the type H brakes on page 3. However, the parking cylinder must be pressurized to fully compress the parking spring (37) during the entire period of reassembly and adjustment. Reinstall hinge pin, adjusting nut and clamp nut. Tighten adjusting nut wrench-tight and then back off nut two and one half turns to provide 1/32" clearance. Tighten clamp nut. Operation and service of the anti-drag assembly is the same as for type H brakes. | |
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