Digging Up the Past

Experimental Hoe-Apron Scraper

In the late 1960s, Caterpillar was pushing to develope a self-loading scraper. After the success of his Triple 657s, he went to work on a new idea. What he came up with was a very complicated but workable idea called the Hoe Apron Scraper. Using a 657, he built a three-jointed backhoe arm to fit inside the bowl with a third engine mounted on the top of the rear engine to run the arm's hydraulics. The design - perhaps his finest - had CAT's engineers scratching their heads over its complex operation. "It was quite an innovation for its time" says Tom Passarelli, a CAT Test engineer who spent 4 years on the self-loading project. "It had a control with 10 micro-switches on it and initially, I couldn't even operate the thing. It was really complicated and that was CAT's biggest concern."

Buster's Hoe Scraper was one of the concepts Caterpillar evaluated in its search for a self-loading scraper, according to Jack Hasten, CAT's Product Div. Mgr. during the 60's. "The way I see it ... it took a genuis to invent it and another genius to operate it." Its advantage was that the 65-cubic yd stretch-scraper could gobble up rocks 4-5 ft in diameter since they didn't have to go through an elevator or auger. In the end, CAT decided against the Hoe Apron Scraper as a self-loading design in favor of a simpler design.

Hoe Scraper Test Crew at Triple J Ranch - circa 1969

Buster Peterson at Center-right ... Vern Renwick next right

"We had to decide which one of the self-loading concepts we would put into production," recalls Passarelli. "We had Buster's Hoe Apron Scraper, CAT's experimental 659 (an elevating 657 scraper), a twin auger scraper, the push-pull concept, and a twin-bowl 657. During the test, Buster's machine looked the best for productivity and projected cost-per-yard, but we ultimately went with the push-pulls because of their simplicity of operation. The Hoe Apron Scraper design was just too complex for mass-production."

Even though Buster's Hoe Apron Scraper didn't make it, Peterson did team up with Caterpillar to create the first Push-Pull scrapers. "Buster may not be on the patent as the intiator for the Push-Pulls but he was the one that developed it to the point that got Caterpillar interested," explains Passarelli. The inital concept came from CAT's Sales Engineering group in Joliet, IL, who put the concept on paper and then worked with Buster to put it into iron. Vern Renwick, Peterson's equipment demonstrator and Special Eqpt Mgr at the time recalls: "I remember asking one of the CAT engineers why they didn't just do it themselves with their vast amount of resources. He said that he wanted the thing in the dirt in 90 days and if he went through the usual bureaucracy, he wouldn't have a fresh piece of paper on the drawing board in 90 days."

Caterpillar's Push-Pull System