Designed to compete directly with the Caterpillar 651, the Euclid S-28, and later S-32 were the largest single-engined overhung scrapers that the company ever manufactured, and as it turns out, also the rarest. By RICHARD CAMPBELL
During the 1960s, there was a surge of interest in really big single-engined motor scrapers.
Projects had gotten much larger and the need to shift bulk earth at a reasonable cost was of great importance to earthmoving contractors.
Caterpillar had gained a bit of a jump on the competition with its model 651 which was first introduced in 1962.
Of these five manufacturers, only Wabco, and to a lesser extent Allis-Chalmers, had any real success in this size category.
Euclid had seen the need for a machine larger than its existing S-24 in 1962 (after Caterpillar had already introduced the 651) and immediately began development of a couple of test “mules” to see how well it performed.
After a few tweaks, the first production machines, now known as the Euclid S-28, made their appearance in late 1963.
The Euclid S-28, as the designation implies, held 28 cubic yards stuck and 38 cubic yards heaped, a very worthwhile payload.
In operational trim, the machine weighed almost 46 tons empty.
The S-28 also introduced a few firsts for Euclid, some of which would be incorporated into other machines in the range.
First of these was a power-down apron.
Up until 1963, all Euclid scrapers featured a cable-operated, gravity-closed apron.
(Some machines, such as the TS-14 still retained this feature up until it was discontinued).
Due to the new configuration of the S-28’s gooseneck, application of a gravity-closed apron was not feasible so another solution had to be found.
The result was the power-down ‘radial arc’ apron.
By 1964, both the smaller S-24 and TS-24 also featured a power-down apron.
(So did the TS-18 which came out in 1972).
Next innovation was the roller push block.
If you have observed for any time push loading of scrapers, you may have noticed that it is possible to lift the rear wheels of the scraper off the ground when loading.
This results in a loss of control over cutting depth for the scraper operator.
Euclid’s roller push block was an attempt to negate this problem, and it worked to a greater extent.
The fact that it did work resulted in the roller push block being made available as an option for all other Euclid scrapers.
The last trick up Euclid’s sleeve was the single lever bowl operation control.
This was a concept ahead of its time and only really recently reintroduced on more modern scrapers.
One lever controlled all functions – bowl lift/lower, apron lift/lower and ejection.
In order to get this rather complex device to work, Euclid engineers employed air boosted servos to the hydraulic valves.
This proved to be somewhat problematic as operators complained that they lost “feel” for the bowl functions.
Previous Euclid scrapers used a direct linkage to the valves allowing minute adjustment by the operator.
The air booster just opened or closed the valves immediately which made for quite jerky operation.
Also, unless the air system was regularly – i.e daily – purged of water, moisture in the air lines quickly corroded the polished surfaces of the valves causing them to stick, with the usual unfortunate consequences.
Euclid offered a multi-lever reversion package to overcome this problem but still offered the single lever control up until the late 1960s and well into the production of the S-28’s successor, the S-32.
Another break from Euclid tradition was the application of a two-piece bowl floor, part of Euclid’s “roll out, snap out” ejection system.
All Euclid scrapers of the 1960s had a curved bowl floor hinged just behind the cutting edge.
Application of a roller lever or direct hydraulic force lifted the floor up and forwards rolling out the load.
Euclid deemed that due to the length of the S-28’s bowl floor, this was not a practical way of getting the load out and so it came up with the two-piece floor.
Instead of having just one hinge behind the cutting edge, it also had another about half way along.
When the hydraulically-actuated roller lever lifted the bowl floor to eject the load, the floor rose and contacted rollers on either side of the bowl top bending the floor in half near the end of the stroke allowing the last of the bowls contents to be “snapped” out.
Great idea when new but repeated banging of the bowl floor against the stops eventually resulted in structural failure.
In fact, structural failures would plague both the S-28, S-32 and the twin powered TS-32 all their operational lives.
Unfortunately for Euclid, the S-28 was not the runaway success it had anticipated.
Caterpillar’s head start, along with strong competition from Wabco, plus operator resistance towards the single lever bowl control system meant that under 200 were ever manufactured, with production ceasing in 1966.
A twin-engined version, the TS-28, was investigated with a few prototypes but not put into production.
The S-32 (an S-28 on steroids)
Euclid did not give up on capturing some of the large single engine scraper market and set about fixing some of the S-28’s shortcomings.
This resulted in the S-32 which was introduced in 1966.
Capacity of the bowl was increased to 32 cubic yards struck, and 43 cubic yards heaped.
In order to shift this higher quantity of material, the engine was changed to a General Motors 12V-71T turbocharged V-12 diesel which pumped out 498 flywheel horsepower.
A larger Allison CLBT5965 six-speed transmission featuring a hydraulic retarder was installed and the entire planetary final drive system was enlarged.
Empty weight of the S-32 was 52 tons, a 6 ton increase over the former S-28.
Multi-lever bowl control was now offered as standard although the single lever system continued to be available as an option.
By 1968, the name Euclid ceased to be used on GM’s range of earthmoving equipment, GM adopting the new name of TEREX.
Production of the (now) Terex S-32 continued as before.
Alas, the S-32 suffered the same fate as the former S-28, with structural failures high on the list and low volume sales.
The S-32 was eventually withdrawn from sale in 1971.
But Wait, There is Another
I have left the rarest of all until last.
This is the SS-28, a 28 cubic yard, three-axle scraper utilising the bowl of the S-28 and the tractor unit of the SS-24 with either GM 12V-71N of Cummins NVH-6 diesel engines.
This machine was designed to take on the Caterpillar 650 three-axle scraper but unfortunately for Euclid, the SS-28 again suffered the same fate as its siblings and is even rarer than the S-28, with under 100 being built.
The New Zealand Connection.
As far as the Author can ascertain, no S-28’s, S-32’s and certainly no SS-28’s were ever imported into New Zealand.
The S-32’s twin engined counterpart, the TS-32, was imported however, and shifted a lot of dirt in the Waikato coalfields. None exist today.
How do I know if its an S-28 or an S-32 if I see one?
Chief spotting differences are as follows: S-28’s have a single exhaust stack and recessed planetary drive hubs. S-32’s have twin exhaust stacks and prominent planetary drive hubs.
For the Model Collector
Against all odds for such a rare type, there is a 1:50 scale model of the Euclid S-28 available, albeit as a watercart.
The model is made by LMF, a French producer of limited edition models and is a hybrid of resin/white metal & brass.
It is beautifully made but horrendously expensive.
I’m hoping to add one to my collection – one day!