Image: A pair of Caterpillar DW10 1N series with very rare (only 10 were ever built) matching LeTourneau model DLS Carryall scraper and PCU. Location of the PCU and exposed cables behind the operator’s head would give health and safety nightmares these days! The push tractor is a Caterpillar D7. Photo: Author’s collection
Caterpillar missed a golden opportunity way back in 1937 when they rejected R.G. LeTourneau’s idea for a motor scraper. By Richard Campbell
It took the company well over a decade to catch up properly, and by that time, there were quite a few other competitors in the marketplace, all vying for sales.
Introduced in 1941 (before the USA went to war), Caterpillar’s first wheel tractor, the DW10 (1N series) was powered by a 90-horsepower, six-cylinder Caterpillar D468 diesel engine with the exhaust pipe exiting the machine under the body like a truck, and a five-speed direct drive transmission.
At this point in the company’s history, Caterpillar did not manufacture any matching equipment such as scrapers, etc., for use with the DW10, instead leaving it up to its other ancillary suppliers – in this instance LaPlant-Choate and LeTourneau – to supply suitable equipment and the controls to operate them.
The new machine featured vacuum-operated Bendix brakes and was very stylishly art deco in appearance, with lots of sweeping curves, and the headlights faired into the front fenders.
WW2 restricted production of the DW10 as Caterpillar’s plant capacity was turned over to the manufacture of much-needed track-type tractors and munitions for the war effort. Despite this, there were just under 1,000 1N- series DW10s manufactured, the last of these being delivered in 1946.
Trailed equipment
Both R.G. LeTourneau and LaPlant-Choate supplied scrapers to match the new DW10, and Athey Products Corporation built a dedicated quarry-side dumping trailer.
LaPlant-Choates’ offering was the model CW-10 “Carrimor”, a 10-cubic-yard heaped hydraulically-operated scraper (also available as the model TW-10 towed scraper), while LeTourneau offered an adaptation of its existing model LS “Carryall” – the model DLS, a cable-controlled scraper which held a similar yardage.
Less than twenty DW10s were delivered with the LeTourneau DLS combination; most users preferring the LaPlant-Choate offering.
Athey’s quarry dumper was known as the PD-10Q and held 10 cubic yards.
Although Caterpillar did not build its own scrapers at this stage, it did manufacture a bottom dump wagon for use with the DW10 known as the W10 Wagon that held 11 cubic yards and was hydraulically operated.
A post-WW2 DW10
Caterpillar designers had not been idle during WW2, and as war restrictions were gradually being lifted, a revised version of the DW10, the 6V series, was released in late 1946.
This was also powered by the six-cylinder Caterpillar D468 engine that had been given a slight horsepower boost and was now rated at 100 flywheel horsepower.
Other modifications, brought about by operational experience with the 1N series and new manufacturing efficiencies, were incorporated into the 6V series DW10.
Some of these modifications included the removal of the headlights from their faired position in the front of the fender to a headlamp placed on top of it on a bracket, and the introduction of rear fenders to protect the operator from flying mud and debris at speed.
The vacuum brakes were deleted, being replaced by a complete air braking system.
Trailed equipment was now limited to the LaPlant-Choate CW10 scraper, Caterpillar having cut its ties with LeTourneau in 1944.
A revised and beefed-up version of the W10 wagon was also offered and this now held 14 cubic yards.
Not a great many 6V series DW10s were manufactured, only 206 in total before the type was replaced by the final production version, the 1V series, in 1947.
This new DW10 was quite a different beast from the two previous models, featuring a scraper of Caterpillar’s own design, the No.10, which held nine cubic yards heaped (or 10.5 cubic yards with sideboards).
It also featured a new diesel engine, the 115-flywheel horsepower Caterpillar D318, which had a larger bore and more torque than the previously used model D468, and a strengthened transmission to cope with the extra torque produced by the new D318 engine.
Design-wise, gone were all the clean curves of the previous DW10s, replaced by a chunky, matter-of-fact-looking machine with an exhaust pipe projecting through the hood.
The all-new No.10 scraper
The No.10 scraper was basically a Caterpillar No.70 towed scraper fitted with rear brakes and a universal hitch. It was all cable-controlled by Caterpillar’s own No.21 double drum Power Control Unit (PCU).
Features of the No.10 scraper included an eccentric cantilever rear stub axle, not supported on its outside, which could be adjusted for odd-sized tyres, and the curved cutting edge, similar in design to the LaPlant-Choate CW10, which the No.10 had replaced.
A revision to the No.10 scraper in 1952 saw the capacity increase to 11 cubic yards heaped (without sideboarding), a switch to a straight 3-piece cutting edge, easier access to the apron sheave tower and the replacement of the adjustable rear axle with a straddle mounted type for added strength.
Design of the No.10 Wagon remained largely unchanged, and capacity remained at 14 cubic yards.
Postscript
The 1V series DW10 remained in production until 1954, when it was replaced by the new, larger, and more powerful model DW15.
Interestingly, for a short period after the DW15 had been introduced (and even though the new machine had its own matched No.15 scraper), the old No.10 scraper remained available for customers who wanted one, no doubt using up old stock!
Only two DW10s were ever imported into New Zealand, both later 1V variants. These were initially sold to W. Stevenson and Son.
For the model collector
Models of the Caterpillar DW10 are not too commonplace, but some have been produced.
The very first was a 1:24 scale item, manufactured by Reuhl Products in the early 1950s and intended as a customer demonstration piece for Caterpillar dealers, although many later found their way into private ownership.
The model was discontinued in 1955, and examples now change hands for silly money these days, usually over US$2000!
On the 1:50 scale front, EMD Models offered an early 1N series Caterpillar DW10 with matching W10 bottom dump wagon as well as a version with a LaPlant-Choate CW-10 scraper. These have all the art deco appeal of the original but appear to have been discontinued by the company, which is a pity as they were well-made, accurate little replicas.
Parting words from Jeremy Sole- a final column