I have what I believe is a 1969 644A Wheel loader that has been a great machine. We are getting it ready for snow season, but towards the end of last year's snow season the brake pedal got very stiff and required way more force than usual to make the machine stop quickly. The feeling is very similar to an old 7.3 IDI f350's brakes when the vacuum pump failed or an old international with a hydroboost system when the power steering pump failed. Is there something that provides braking assistance in these deeres? This is not an air or air assist system either. Any thoughts or insight would be great!
Power assist comes from the brake/steering pump mounted under radiator to the engine. You will need to check pressures. Brake outlet pressure needs to be 2000 psi min with brake applied. Also need to check that the pressure is getting into the brake valve.
Thanks!, Power steering is also weak and that would make sense. I need to get a pressure test kit now.
Both the brakes and steering have accumulators in the systems. They are located on the wall behind the seat. They are pre-charged with nitrogen at about 500 PSI. Do the easiest things first, like changing the brake and steering filters. Then check the pressures. Do not replace anything until you have definitely found the problem. Pressure testing the system should define the source of the problem so it can be fixed.
Thanks for your insight. I was thinking of that myself and have not yet dug into the project yet. I did get Deere replacement filters. I think the last time we serviced the machine we used Hastings. Not sure if that would make a difference or not. I also have a pressure test kit but I think the Deere manual specified a Deere adapter to test pressure at the pump. Do you know if I can test for the same specs anywhere else in the system without special adapters?
Your local hydraulics store typically has all the adapters you need. Different test points require different adapters. Personally, I own one long test hose (20 feet) rated at 6,000 PSI. I can change from high pressure to low pressure gauges on one end, and adapt on the other end to the test point. Deere charges multiples of the local supply store prices. Over time you will accumulate them as needed for the machines you have. Just be certain the fittings, hoses, and pressure gauge are rated higher than the pressure to be measured. Get the manuals for your machine. There is one on diagnosis and measurements. It will give you the expected performance parameters at test points under the conditions specified. The repair manual only provides physical measurements of components, springs, parts and torques. As for different filter manufacturers, most all are interchangeable without causing issues until they get clogged.