There is nothing quite as good as when an equipment manufacturer ‘gets it right’. Wabco’s model 353FT elevating scraper is an excellent case in point. By Richard Campbell.
Wabco had a very long history of manufacturing elevating scrapers, the first machines being sold in the early 1960s with Hancock bowls in place of its usual cable-operated conventional scrapers. Wabco’s machines were well ahead of their time with this concept, and the company aggressively marketed the elevating scraper idea from then on. Despite early low sales coupled with the inevitable teething troubles, the machines got better and better with a corresponding increase in sales which soon eclipsed that of their conventional open bowl scrapers.
Things progressed steadily into the 1960s with Wabco introducing new models of elevating scraper every couple of years until 1967 when it brought out the model BT333F. Quite unlike anything the company had offered before, the BT333F was powered by twin GM 12V-71N engines putting out a combined 900 flywheel horsepower and weighed some 52 tons empty. This was a 34 cubic yard, twin-engine elevating scraper and the first large elevator to be marketed by any equipment manufacturer. The BT333F was aimed squarely at the mining and volume earthmoving sector and was well-received by both.
As Wabco were operating in hereto unknown territory with a machine of this complexity, size and productive capability, changes to the design were inevitable and it was not too long before a newer variant of the BT333F appeared. This was called the model 333FT and it first appeared in 1970. Initially retaining the same 12V-71N engines and 34 cubic yard capacity of the BT333F, the 333FT was soon upgraded to the more powerful turbocharged GM 12V-71T engine with a combined output of 934 flywheel horsepower.
Weighing approximately 56 tons, the model 333FT was a very popular machine and highly productive in service being capable of loading in rock cuts on its own which would have normally required the use of a push dozer if conventional scrapers had been used. It was also well-liked by operators, and apart from some minor structural problems on earlier machines in the steering cylinder area (which were addressed by improving the casting process), mostly trouble free.
In 1976, Wabco engineers began to improve upon the 333FT by designing an even better machine which was (now) based on sound field experience which had been gained with the earlier BT333F and 333FT. The result was the model 353FT, subject of this month’s article, introduced in 1977. With a 36 cubic yard capacity and a combined 966 flywheel horsepower available from its two GM 12V-71T diesel engines, the 353FT was the apex of Wabco’s elevating scraper technology.
Attached to each engine was an Allison VCLBT-5965, six-speed powershift transmission. These were state-of-the-art gearboxes and featured a variable input torque converter, two loading ranges especially designed for elevating scrapers, and an in-built hydraulic retarder to save on brake wear during downhill hauls.
The tractor unit had been totally redesigned and was not a modified 333FT tractor unit. The previous bull gear and pinion final drives common to former Wabco machines were replaced by planetary final drives all round although the Wabco no-spin differential of previous machines was retained.
Even though it was a big machine, the 353FT was no slouch on the haul road and capable of speeds in excess of 34 mph (56km/h) loaded. It also rode extremely well, endearing it to those who were fortunate enough to operate it.
The bowl, which held 36 cubic yards (two more than the previous model 333FT), was of double wall construction and had a 3-piece cutting edge which could be fitted with five teeth if necessary. Of obvious Hancock parentage, the bowl resembled that of Wabco’s recently introduced but smaller model 252FT (featured in the October 2021 issue of Contractor).
The 3534FT’s bowl followed the typical Wabco format and had a fixed cutting edge with a sliding floor and drop-down strike off plate to help level the dumped material as it fell out onto the fill. A hydraulic bulldozer-type ejector took care of the past few yards in the bowl.
While earlier Wabco elevating scrapers had utilized a large generator to operate machine functions, the 353FT required only a smaller generator which only supplied power to the elevator motors.
The 353FT was a big, mean looking machine and was all business. This was going to be a world beater for Wabco, but as fate would have it (and extremely unfortunately for Wabco), the world entered a particularly large recession in the early 1980s affecting mining and large earthmoving projects worldwide and sales of big machines such as the 353FT pretty much dried up overnight.
Wabco’s principal competitor in the large elevating scraper market, the Caterpillar 639D, also suffered the same fate. Wabco, whose prime business focus from the mid-1970s onward had been mining trucks and large construction equipment was faced with a massive loss of earnings and one from which the company could not recover despite closing its manufacturing facilities in Brazil, Australia and some plants within the continental USA.
Wabco ceased trading in June 1984 and the company’s assets were split over two of its more liquid competitors, Komatsu and Dresser Industries but neither of these two wanted to re-invest in Wabco’s elevating scrapers and the type disappeared from production forever.
The Wabco 353FT was manufactured solely in the USA although four units were supplied via the USA out of Australia with Australian serial numbers. Total production of the 353FT was under 50 units.
The New Zealand connection
Goodman Contractors of Waikanae are the proud owners of two Wabco 535FT elevating scrapers that were previously owned by Footstool Earthmoving in Australia. They have both been totally overhauled to “better than new” condition and put to work by their new owners, who have been long time Wabco users and enthusiasts.
For the model collector
Sadly, there are currently no models of the Wabco 353FT available in any scale. For such a ground-breaking (literally) machine, this is a travesty but a situation unlikely to improve in the near future. Models of Wabco equipment in general are very few and far between and in the realm of the boutique model manufacturer who regrettably charge moonbeams for what few Wabco items that are produced.
Engines (front): General Motors 12V-71T turbocharged V12, 2-cycle diesel engine rated at 493 flywheel horsepower at 2100 rpm.
Engines (rear):General Motors 12V-71T turbocharged V12, 2-cycle diesel engine rated at 473 flywheel horsepower at 2100 rpm.
Transmissions: Matching Allison VCLBT-5965, 6-speed full powershift transmissions with variable input torque converter and in-built hydraulic retarder.
Differentials: Wabco self-actuating traction sensing type (no-spin).
Brakes: Air over hydraulic shoe type on all four wheels.
Std.Tyres (tractor): 37.5×39, 36-ply E-3, (scraper): 37.5×39, 44-ply, E-3.
Top Speed: 35 mph.
Capacity: 36 cubic yards.
Operation: All hydraulic apart from elevator drive.
Elevator drive: Two Wabco 7N6 electric motors.
Elevator Flights: 16, each 8’ wide.
Cutting Edge: Single center edge with two end blades. Center edge has the option of being fitted with five teeth to break up particularly cohesive soil.
Length: 50’ 4”.
Width: 13’ 2”.
Height: 14’ 2”.
Weight: 62 tons empty, 105 tons loaded.