Hyster H50H.D3T1875V:
Hydraulic/ Brakes/Power Steering Issue

Hi all, just joined as I am trying to troubleshoot a hydraulic issue on what I think is a H50 (ID plates are gone). It has 2 speed forward/reverse with a hydraulically assisted clutch that makes it easier to push clutch pedal down. Power steering is hydrostatically driven. 4 cylinder continental gasoline motor.

It was fully functional until I went to park it. Went to push down the clutch and promptly drove it into a fence because the clutch would not go down due to the hydro assist not working.

Its current state is the hydro assist clutch is not working, as well as the power steering is not working either. The mast tilt and up/down work perfectly.

Heres the kicker. When I push the lever to tilt the mast forward or backward, while it is tilting, the hydro assist for the clutch works. As soon as I stop tilting, the hydro assist stops working and the power steering stops working.

The hydraulic fluid was about 2 gallons low. I added fluid after this started happening, nothing changed.

Any advice? I am mechanically able but this is the first time I have worked on forklift hydraulics and am not educated on the subject.

Just bought the forklift a few weeks ago, everything was working prior to yesterday!

Thankss!
  • Posted 12 Sep 2014 10:46
  • Modified 12 Sep 2014 15:06 by poster
  • Discussion started by Brandon
  • California, United States
Showing items 1 - 11 of 11 results.
I used to have this problem now and again on the XL range (yes i know the HH is completely different) check the seals on the flow divider on the XL if they failed where it was bolted onto the pump the steering wouldn't work until you operated an hydraulic function How many outlet pipes have you on the pump??
  • Posted 20 Sep 2014 18:49
  • Reply by lifter01
  • West Yorkshire, United Kingdom
I ended up removing the hydro pump and taking apart the head. It does not appear to be a dual pump, but there is a spring loaded mechanism going across the two ports that the hoses attach to. I am going to clean it and reassemble, but nothing really stood out as being wrong.

I am also going to take apart the valve assembly for tilt/lift functions and see if I can find anything..
  • Posted 15 Sep 2014 03:43
  • Reply by Brandon
  • California, United States
brandon
on this hydraulic pump does the line for the brake/ps circuit attach to the end of the pump or maybe a 2nd section like a charge pump?
it could be what bbforks says and there may be a 2nd relief valve for the auxillary circuit but if this pump is a dual pump it could be the section supplying the brake/ps circuit might be bad.

just a thought
  • Posted 14 Sep 2014 14:22
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com
The older Hyster's I've worked on had separate pressure relief valves for each control valve when set up in the way you describe.

If the p/s & clutch work when the tilt is operated I would check the relief valve in the main contol valve. Perhaps someone on this site would know the pressure settings.
  • Posted 14 Sep 2014 12:52
  • Reply by bbforks
  • Pennsylvania, United States
bbforks (at) Hotmail (dot) com
Customers love technology- until they have to pay to fix it!
The older Hyster's I've worked on had separate pressure relief valves for each control valve when set up in the way you describe.

If the p/s & clutch work when the tilt is operated I would check the relief valve in the main contol valve. Perhaps someone on this site would know the pressure settings.
  • Posted 14 Sep 2014 12:52
  • Reply by bbforks
  • Pennsylvania, United States
bbforks (at) Hotmail (dot) com
Customers love technology- until they have to pay to fix it!
I traced the supply line from the aux control valve( for p/s, power brakes. It leads directly to the head of the hydraulic pump. There are two lines going to the head of the pump, one to the p/s, power brakes valve, and the other going to the tilt, lift valve for the mast.

So it looks like the diverter/proportioning valve is inside the hydro pump. Is the pump something I can take apart or will all **** brake loose? It looks like the head of the pump pops off easily, I just am afraid that the head is centering/retaining parts inside the pump.

Cheers!
  • Posted 14 Sep 2014 07:40
  • Reply by Brandon
  • California, United States
There should be a flow divider in the pressure line to the 2 different control valve assy's. Since the p/s & clutch come to life if you use the tilt it seems like the flow divider is having an issue. Follow the pressure line from the hyd pump & you should find it.
  • Posted 13 Sep 2014 00:59
  • Reply by bbforks
  • Pennsylvania, United States
bbforks (at) Hotmail (dot) com
Customers love technology- until they have to pay to fix it!
the one for the power steering and brake lines go to is the one i'm speaking of. It may be refered to as the auxillary hydraulic control valve or steering priority valve. Without a manual to look in to see what exact terminology they are calling this i do not know for sure.
No manual on hysters website, the unit is too old.

look on that valve assy though and see if there are any check valves on it, or plugs that may contain a check valve.

chances are you will find one stuck or broken.

no direct lines connecting the two? it has to be getting its fluid from somewhere.
  • Posted 12 Sep 2014 20:54
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com
Wow thanks for the quick replies. I did find the serial number. It is B3D-3462L

Swoop223, There is a valve assembly towards the right side of the lift under dash that tilt controls go into. There is also a valve assembly to the left under dash that power steering lines and brake assist line go into. I did not see any lines connecting the two but I am not certain. Can you specify the proper name for each/are these what you are referring to?

Thanks!
  • Posted 12 Sep 2014 14:30
  • Modified 12 Sep 2014 14:40 by poster
  • Reply by Brandon
  • California, United States
being that the brake is hydraulic assisted i would look at the auxillary circuit off the hydraulic control valve. It should have a check valve on it or a pressure relief valve, i would check those to see if there is a broken spring or a stuck check ball or something like that.
  • Posted 12 Sep 2014 13:05
  • Reply by swoop223
  • North Carolina, United States
You've been swooped!
swoop223@gmail.com
With out knowing the model and serial number not going to get much help....at least a serial number will help,it should be stamped into the frame someplace on the truck,places to check are on the front cowl just behind the mast....also on the top of he frame either on the left or right side,might have to scrape and clean crud and rust to find it but it should be stamped some place...check on the right hand side of the frame either on the side or top of the frame under the good....
  • Posted 12 Sep 2014 11:46
  • Reply by kevin_t
  • Pennsylvania, United States

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