Incompatible Hydraulic Couplers

ISO 5675 (Ball, AG type) vs. ISO 7241-1

A Case where the Two are NOT Compatible

August 2021

I have a Case IH C80 tractor, and have used various agricultural implements with it for close to 30 years. Some of those implements have ISO 7241-1 (poppet) type male hydraulic fittings, and some have ISO 5675 AG (ball) type hydraulic fittings. All have worked fine with the tractor, regardless of the male fitting type.

Male Ball Coupler
ISO 5675 Ball (AG Type)
Male Hydraulic Coupler
Male Poppet Coupler
ISO 7241-1 Poppet
Male Hydraulic Coupler
Tractor Female Coupler
C-80 Tractor
Female Hydraulic Coupler

Two years ago I purchased a Wallenstein BX52-R chipper. The chipper came with ball type fittings, and at first blush seemed to work fine. However, I soon discovered I had problems.

The chipper flywheel with cutting blades is hooked to the 540 rpm PTO on the tractor, while the branch feeder is driven via a hydraulic motor hooked to a pair of remotes. That has the tractor engine running at 2000 rpm to get the proper speed on the PTO. But at 2000 rpm there is too much hydraulic pressure, and pretty soon the return flow male hydraulic line quick disconnect from the chipper jams closed — while still properly engaged in the tractor hydraulic port. The rollers feeding branches into the chipper freeze up, and the control arm to forward feed / reverse feed / disengage the branch feeder seizes up and becomes very difficult to move. Sometimes a chunk of branch will break off and lodge / do barrel rolls inside the feeder, and that also jams the feed and jams the return hydraulic line. The size of the branch being chipped doesn't matter; a 1-1/2" branch will jam it just as easily as a 5" branch, and a green branch will jam as easily as a dry one. In all cases, the tractor pressure relief valve would open up since the return line is blocked with the return line male quick disconnect ball closed.

The chipper feed seemed to work a bit better if I ran at lower rpm, but then the chipper wouldn't throw the chips very far and jammed easier in the outflow chute. I tried adjusting the rate of feed but that had no affect on the problem.

The jam could be cleared by disengaging the rear remote, disconnecting the return hydraulic line, slamming the ball against a flat metal surface to cause it to open up enough to relieve the pressure, moving the chipper infeed control to the "reverse feed" position so it will back out the jammed branch when started up, reconnecting the hose, and re-engaging the hydraulics.

It took me forever to figure out what was going on. For some reason, hydraulic pressure in the return line was overpowering the spring on the poppet in the tractor female remote, which is supposed to keep the ball depressed (open), so the ball in the male fitting would close.

I finally decided there must be some problem with the ball type male connection on the chipper, and replaced the return flow ball type connector with a poppet style. Voilą! That totally solved the problem. and the poppet type doesn't.

I found these pages showing the inside of the various couplers:

In the diagrams on the above pages, there is clearly a different distance, or at least positioning, between the various types of connectors. The positioning of the balls and poppets is different in the different connectors, and the male poppet sticks out farther than the male ball. The female poppet in the A and B versions is located in a different position, and both are different from the female ball. So if any two types of male and female are mixed, the dynamics under pressure will be different and could cause flow problems that could potentially result in a lock-up at high flows. In addition, the standards may have different pressure requirements for the female end springs that hold the valves open.