Although the Cat 630A was a significant improvement on its predecessor, it didn’t have hydraulic controls and was soon surpassed by the 630B. By Richard Campbell
In order to remain competitive in the rapidly evolving motor scraper marker, early in 1959, Caterpillar began a fairly radical redesign of their popular DW20 series G tractor scraper.
The end product was the model 630A, introduced in 1960, second in the 600 series of Cat motor scrapers (the first was the 619).
Closely resembling its predecessor externally, the 630A was in fact quite a step forward for conservative Caterpillar in a number of areas.
Replacing the former DW20’s Cat D337 diesel was the new model D343T, a six-cylinder, in-line, turbocharged and after-cooled diesel, featuring twin overhead camshafts. The D343T was rated at 335 flywheel horsepower and was connected to an all new Caterpillar nine-speed barrel type powershift transmission with a torque divider for maximum use of available power.
Another innovation was the use of planetary final drives, a first for Caterpillar on a three-axle scraper.
A considerable amount of attention was paid to the styling of the tractor unit. Gone was the angular somewhat austere look of the DW20, replaced by more flowing, rounded lines and a nicely sculpted bonnet and radiator guard.
Fenders were fitted as standard to both driving and steering axles to prevent splashing the operator.
The operator’s area was very neat and tidy with a good deal attention paid to the physical demands of the operator, including a shock absorbing seat. All controls were within easy reach and a full set of gauges was fitted in a well laid out dashboard.
The steering axle was similar to the DW20’s but was physically bigger and had a better mounting. Power steering was provided via a Vickers steering booster.
Brakes were air operated shoe type on the drive and scraper axles, synchronized to brake scraper axle first to help prevent jack-knifing on the haul road (a potentially fatal situation in a machine like the 630).
With all these changes to the tractor unit logic would dictate that the scraper would also have had an extensive makeover but, regrettably, this was not the case. At a time when all of the major scraper manufacturers (besides LeTourneau-Westinghouse) had converted to full hydraulic control for their scrapers, Caterpillar was still firmly entrenched in the 1940s, utilising all cable control.
Two kinds of lowbowl scraper were offered for use with the 630A – initially the 27 cubic yard, struck 35 cubic yard heaped No.482 series C, and soon after the model 630A rated at 21 cubic yards struck and 28 cubic yards heaped.
Both the No.428C and 630A scrapers featured an air operated cable saver device to prevent double-blocking and subsequent cable breakage.
Despite the outdated scraper, the 630A was well accepted by the contracting community and sold well for the reasonably short time the machine was in production.
A number of ancillary manufacturers offered optional trailing units for use with the 630A tractor, most notably Athey who produced rear dump, bottom dump and side dump wagons in their PR range of equipment.
The Hyster company, better known for its forklifts and logging winches, manufactured a double drum sheepsfoot roller for use with the 630A tractor.
It would appear in hindsight that Caterpillar could see the writing on the wall in regard to hydraulics and scraper operation as the 630A was only in production from 1960 through to 1962 when it was replaced by the 630B – a machine with all hydraulic functions.
Notwithstanding its good looks, the Caterpillar 630A should probably be best viewed as an interim machine – a proving vehicle and prototype for what was to follow.
The New Zealand Connection.
Believe it or not two Caterpillar 630A motor scrapers made it to New Zealand and were delivered by Gough, Gough and Hamer to W. Stevenson & Son of Auckland.
These machines were put into operation at the company’s vast opencast coal mine at Kopuku in the northern Waikato. They were also used in the construction of the Drury to Bombay section of the Auckland motorway system.
Both of these machines were fitted with the smaller 21 cubic yard 630A scraper.
When Stevensons closed down its Kopuku operation the machines became surplus to requirements and were sold. The author believes that one still exists intact in the Otago region of the South Island.
Brief Specifications – Caterpillar 630A
Engine: Caterpillar D343T six-cylinder, inline, turbocharged and after-cooled diesel, 335 flywheel horsepower
Transmission: Caterpillar nine-speed full powershift with torque divider
Steering: Power boosted
Brakes: Air operated, expanding shoe type
Std.Tyres: Steering: 16:00×25, drive: 29.5×35, scraper: 33.5×25
Top Speed: 40 mph
Hitch: Cast, universal kingpin type
Control: Air boosted double drum Caterpillar 127 cable control
Capacity: 21 cubic yards struck, 31 cubic yards heaped
Length: 45’ 4”
Width: 11’ 9”
Height: 12’ 3”
Operating Weight: empty: 31 tons, loaded: 59.6 tons