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| Air over hydraulic brakes |
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| Tow hook added |
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| Strut suspension |
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| Emergency Shut down on engine |
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There was a time when Westinghouse Air Brake Company fancied itself as a contender in the heavy machinery business. To this end they acquired a number of heavy equipment manufacturers including R. G. LeTourneau, Wagner, and others which became a subsidiary which marketed machinery under the name of WABCO during the from 1953 into the 1980's. Among the things manufactured over a fairly extensive period of time were Rock trucks of which the model 30 was the smallest.
As the model number implies it is a 30 ton model meaning that it will haul 30 tons nominally. It weighs around 25 tons. The particular model featured here is believed to be a 1964 version confirmed by the trim. Dual headlights are very early 1960ish.
The engine is a Detroit Diesel 6-110 which was not produced after 1965 which tells us that it is unlikely that this truck is newer than that although the model number was produced into the early 1980's with other more powerful engines. The DD 6-110 is a classic in-line 6 engine designed as a 6-71 on steroids. DD took the classic 6-71 and added 50% to it. Most of the accessories are compatible with other DD engines, but there is no mistaking the basic engine as being larger.
This particular model features an Allison 6 speed Automatic transmission. The rear axle assembly includes inboard final drives with the bull gear to the rear of the differential. Service brakes are provided by air over hydraulic wedge brakes. It is a dual system. Pressure limiting on the front brakes is available to the operator via a flip switch and as a result there are a total of 4 air over hydraulic master cylinders. An air released, spring set parking brake is provided on the back of the transmission, and a temporary parking flip switch is provided to the operator that only works if there is air pressure. Historically the brakes have been a major maintenance item. It took two mechanics about a week to get the brakes working properly when we purchased truck when it was a mere 45 years old. We found a wrong valve in one place and several valves were leaking and an air line or two were not hooked up in the right place. Once we got the brakes working, they would slide the wheels at least when the truck was empty. The main problem is that the plumbing is so complicated that it is confusing. The hydraulic brake subsystem is broken down by brake shoe with each of the 4 master cylinders operating 2 shoes on opposite wheels. The air system is dual complete with about 4 air tanks and 2 relay valves.
Tires are 18x25 all the way around, but the front and rear wheels are different.