Image: Oliver promotional photo of an OC-18, taken on a highway construction job in the USA. The machine has a Heil cable-controlled straight blade with the cable control mounted on the rear. The area just in front of the operator housed the machine’s fuel tank which held 66 gallons. The operator doesn’t look too enthusiastic. PHOTO: AUTHOR’S COLLECTION
The Oliver OC-18 was the largest track-type tractor Oliver ever produced and was unique due to an early type of power steering, writes Richard Campbell.
Back in their heyday, the Oliver Corporation of Cleveland, Ohio, USA, were a well-respected company manufacturing agricultural tractors and implements. Looking to expand their marketplace options beyond agricultural wheel tractors, they acquired the Cletrac Tractor Company, also of Cleveland, Ohio, in 1944.
The Cletrac Tractor Company had fallen on hard times during World War II, being one of the few tractor manufacturers not to be given large US Government contracts for the production of machinery, so the sale to Oliver was very timely and prevented the company from going into bankruptcy.
Cletrac had quite a long history dating back to 1916 and were one of the pioneers in the track-type tractor industry.
In fact, Cletrac were the first company to manufacture a “hi-drive” (elevated sprocket) track-type tractor on a production basis – their Model F, which was produced from 1920 to 1922, pre-dating the Caterpillar D10 by 57 years!
The Model F was a small crawler tractor strictly speaking, only suitable for agriculture, and weighed around 900 kilograms, but could pull a three-bottom plough with no trouble.
One of the hallmarks of Cletrac tractors was their reliability, especially their final drives. This was due to the way the track frames were mounted to the chassis by way of a dead shaft.
Using this method, no impact shocks were transferred through to the final drives.
This mounting also allowed a higher than usual amount of ground clearance, making Cletrac machines especially popular with logging and forestry contractors, as they could pass over stumps and brush that could potentially bring other tractors to a very sudden stop!
Other track tractor manufacturers took a long time to duplicate this method of undercarriage attachment, with the first to successfully adopt it being Euclid in the mid-1950s.
From 1936 until Oliver bought them out, Cletrac used an alphabetical system to identify individual models within their product range e.g.: Model BD, Model DG, Model AG etc.
When Oliver took over the Cletrac tractor range it consisted of some 12 different models, some gasoline-powered, the others diesel.
Oliver kept the Cletrac name, marketing them as Oliver-Cletrac so as not to confuse the buying public, and it was back to business as usual.
Oliver makes some changes
In 1949, it was decided by Oliver management to add some clearer structure to the model numbering system, better reflecting the sizes of machines offered.
The Cletrac name was dropped altogether, and a new machine identification system “OC” (Oliver-Cletrac) prefixed all the track-type tractors.
With this system in place, machine models included the OC-3, OC-4, OC-9, OC-12, OC-15 and our subject for this month, the OC-18.
As a company, Oliver did not expend great amounts of research and development money into their OC track tractor range and as a result, this allowed other manufacturers to gradually move ahead of them technically.
Sales of track-type tractors started to decline as the existing machines were being surpassed by competitors’ better technology.
The situation finally came to a head in 1960, when Oliver itself was bought by the White Motor Corporation. White continued to operate Oliver as a going concern but was also reluctant to spend the large volumes of cash required to update the Oliver track-type tractor range or produce any new machines.
The end result was that in 1965, production of all Oliver track-type tractors was discontinued; the company preferring to concentrate on agricultural wheel tractors.
Description of the model OC-18
Weighing some 16 tons bare, and the largest track-type tractor that Oliver ever produced, the model OC-18 sat between D7 and D8 sizes in the track tractor world, and some 800 OC-18’s were manufactured between 1951 and 1959.
The OC-18 had originally started life as the Cletrac model FDE in 1945 but was extensively redesigned by Oliver engineers and reemerged as the Model OC-18 in 1951.
Oliver used a Hercules model DXFE diesel engine in the OC-18. It was a six-cylinder inline diesel putting out 161 flywheel horsepower and had a 14.7-litre displacement.
A double plate clutch connected the diesel engine to the four-forward, two-reverse speed manual transmission, which gave the machine a top speed of 5.4 miles per hour.
Oliver was unique in the American track-type tractor market because it used differential steering rather than the traditional clutch and brake steering method.
Cletrac had pioneered the use of differential steering decades beforehand, and it was carried over into the OC range of machines. It wasn’t until the 1990s that other manufacturers began to use this steering method.
The OC-18 was a 78-inch-gauge tractor and utilized a six-roller track frame with two carrier rollers per side. Track links were 35-section, and the standard track shoe was a single grouser, 26 inches wide.
As mentioned previously, the track frame was isolated from the final drives and attached to the chassis by means of a large dead shaft, which, along with the multi-leaf equalizer spring, allowed track oscillation of some 13 inches.
A good spotting feature of the OC-18 was its long front hood, the rear part of which housed a 66-gallon diesel fuel tank. Oliver supplied their larger crawlers with a distinctive opposed Chevron design radiator guard. The OC-18 was no exception, and this is another good spotting feature.
The operator had an excellent view to trailed equipment as there was no fuel tank to look over. However, the view forward was a long one, and the hood did not feature any taper to improve forward visibility.
Operator comforts were very few, other than a deeply padded seat and air-boosted steering levers to reduce effort. This was an unusual feature for a track-type tractor and something that set the OC-18 apart from the competition.
An engine-driven air compressor provided constant pressure for the system. Full instrumentation was provided on a semi-circular instrument panel in the centre of the dashboard.
Equipping the OC-18 for action
Oliver, like almost every other track-type tractor manufacturer of the 40s and 50s, did not make its own attachments, relying on outside suppliers to provide bulldozer blades, rippers, scrapers, cable controls, winches and the like to equip their machines for service.
Oliver’s principal suppliers were Heil, Isaacson, Buckeye and Carco, with the most predominant of these being Heil.
The New Zealand distributor for Oliver back then was Frederick W. Smith Ltd. Regrettably, no records have survived from this company to give any indication as to how many Oliver OC track-type tractors were imported, including (if any), OC-18s.
There were, however, many of the smaller Oliver OC tractors imported and sold, a lot into agriculture in the South Island.
For the model collector
No models of the Oliver OC-18 exist to the best of my knowledge. There is, however, a very good model of the smaller model OC-12 available from Spec-Cast, but it was a limited run item. This is to 1:16 scale and is available with or without a Heil hydraulic blade.
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