Advice worth the price of a tractor
It might have been the end of the line for the old tractor. Instead, with advice from near and far and a single flat washer, the tractor has a shot at another seeding season.
The problem was evident as soon as we hooked to the new-to-us seed drill. The drill lifted just fine, but it wouldn’t fold. The hydraulics on the 875 Versatile built in 1980 didn’t have enough lift for the wings of a K-Hart drill from 2012.
Another tractor was used to fold the wings and we pulled the drill home to ponder the problem.
As I talked with the guys on coffee row, I learned that you could easily measure hydraulic pressure with a gauge inserted in the tractor coupling. A neighbour lent us a gauge and we soon found the tractor was putting out only 2000 psi.
The instruction book says the tractor is rated at 2300 psi, so what was the problem – filter issues or maybe a weak hydraulic pump? I posed the question on Twitter and suggestions came pouring back.
One response suggested the solution was to buy a new tractor for $600,000. Another said that new hydraulic pumps are about $10,000 installed. Yet another said that he didn’t think hydraulic gear pumps were still available for such an old Versatile.
Well, maybe it was just a filter issue. No probably not said another Tweet. A filter restriction would reduce the flow, but in most cases it shouldn’t reduce the pressure.
As you can probably tell by now, equipment repair is not my strong suit. A mechanic I am not.
But a young mechanic called my cell phone. He had seen my Tweet and had fixed a hydraulic pressure issue on our Apache sprayer. The tractor is probably twice as old as this mechanic, but he went back and forth with us trying to locate a pressure relief valve. He even talked about using shims in the valve to boost the pressure.
No valve on or around the hydraulic pump. Despite what the instruction book says, no relief valve at the front of the oil reservoir. The neighbour who lent us the pressure gauge used to run a similar old Versatile and he remembered a relief valve on the hydraulic spools behind the cab.
We had removed a panel and closely examined this cluster, even getting schematics emailed from a couple of dealerships. The schematics were a different orientation and with all the parts fitting into other parts, the diagram wasn’t that useful. And it didn’t really list anything described as a pressure relief valve. We unscrewed some big plugs, but no relief value.
We pondered the problem with our neighbour and he suggested the valve might be located between the spools and the back of the cab. We might be able to get to it by removing another panel.
He was right. When we got it out, we discovered “2300” stamped on the end. We took the valve apart and added a couple of small washers on top of the spring. That shot the pressure up to 3000 psi. Impressive, but way above system specifications.
We went with just one flat washer, about the size of a dime, giving us 2500 psi and just enough pressure to fold the drill. An amazingly simple and cheap fix, but we’d have never figured it out without neighbours, both close-by and on Twitter.