1995 - Volume #19, Issue #5, Page #33
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Tractor Converted To Hydrostatic Transmission
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Alan Smith from Mintaro, South Australia, is a custom hay contractor who makes about 8,000 big round bales a year for customers. The problem was that he had to replace at least one clutch a year on his Chamberlain C6100 tractor which pulls the baler (Chamberlain is the name Deere tractors are sold under in Australia).
Alan finally decided he could solve his problems by replacing the conventional transmission in his tractor with a hydro-static one.
Fortunately, he says, the tractor was constructed with a separate sub frame so he could remove the entire transmission (in other words, the transmission was not part of the tractor's support structure).
The second stage of the conversion was to couple a Rexroth hydrostatic pump directly to the engine flywheel. He had to use a large enough pump to match the 3,000 rpm speed of the input shaft into the rear 3-speed gearbox. The pump powers a fixed displacement hydrostatic motor that's fitted directly to the rear gearbox.
The conversion gave him infinitely variable speeds within three speed ranges, whether moving in forward or reverse. A single hydraulic lever controls speed within each range. Maximum speed in the low range is about 7 mph; maximum speed in mid-range is about 14 mph; and maximum speed in high range is about 32 mph.
Due to the size and capacity of the pump, Smith had to install a larger cooling system. A 25-gal. oil reservoir mounts on the side of the tractor while an oil cooler and fan, powered directly off the crankshaft, were mounted on the front left side of the tractor.
With the main transmission gone, there was no pto drive so Smith mounted a triple pulley on the back of the hydraulic pump which belt-drives a new shaft that runs back to the original pto drive. The cost of the modification was about $12,000. Smith claims the converted tractor is superior even to tractors with the latest model trans-missions since the hydrostatic transmission gives him infinitely variable speeds in either direction. When he ran in a test against a conventional tractor pulling the same model baler, he was able to make 50 per-cent more bales in the same amount of time.
Contact: FARM SHOW Followup, Alan Smith, Mintaro, South Australia, Australia.
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