10 x 4, 14 x 6 And 18 x 8 Type HM Brakes | |
| Except for an added spring-applied, hydraulic-released HM parking cylinder, type HM brakes are identical to type H hydraulic-applied brakes. Type HM brakes are adjusted in the same way as type H brakes. However, it is essential that the HM parking cylinder be kept fully released and that .010" clearance exist at the top of the HM cylinder (see illustration) during the entire adjustment procedure. Replacement of the brake shoes and service of the self-centering mechanism of the hydraulic brake cylinder is the same as for the type H brake. |  |
SERVICING THE HM PARK RELEASE CYLINDER | |
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The HM park release cylinder applies the brake with heavy spring force that is held released by continued application of hydraulic pressure. After continued use the hydraulic seals wear and the parking cylinder must be removed for service or replacement.
To remove the HM parking cylinder, first disconnect and temporarily cap the hydraulic line at the brake hose. Then loosen the adjusting nut (16) until the fully extended HM cylinder is unable to apply force against the top brake arm. Now, remove the bottom mountinging. |
The 14" and 18" HM cylinders can be removed by slipping the piston rod out of the tubular push rod. The 10" HM cylinders must be separated by unthreading the piston rod guide out of the rod end. The replacement or repaired HM cylinder should be reinstalled in reverse order to the above. The brake should be readjusted after the cylinder has been reconnected into the system, the hydraulic circuit has been completely bled, and with the HM cylinder held released with hydraulic pressure. |