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jpi72 
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Joined: 27 Jul 2019
Location: Hudson, Iowa
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 Topic: Power Steering issue
Posted: 31 Dec 2024 at 6:21am |
I own an Allis Chalmer forklift (621?). We are having issue with the power steering when we start in the morning, especially when it is cold. The steering does not work for a while. After a few minutes it does work. This forklift has a lot of d15 parts. My son thinks it is a relief valve issue. Do you have any suggestions? The hydraulic lift works fine when the power steering does not work. Joel
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DrAllis
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Joined: 12 Sep 2009
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Posted: 31 Dec 2024 at 9:48am |
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NOT a relief valve issue. The hydraulic/power steering pump is losing its prime when sitting for extended periods of time. Cold weather makes it worse. Do the other hydraulic functions work when the steering doesn't ??? I would bet they are dead too. Is the hydraulic tank FULL ?? Is there a suction filter in the hydraulic tank ?? I still think you have a "worn out pump" scenario.
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ekjdm14
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Joined: 20 Aug 2024
Location: Manchester UK
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Posted: 31 Dec 2024 at 11:23am |
 DrAllis wrote:
Do the other hydraulic functions work when the steering doesn't ??? I would bet they are dead too. Is the hydraulic tank FULL ?? Is there a suction filter in the hydraulic tank ?? I still think you have a "worn out pump" scenario. |
jpi72 wrote:
The hydraulic lift works fine when the power steering does not work. Joel |
I'd agree it's not going to be a relief valve, but assuming the other hydraulics are working when steering is dead then it's surely less likely to be an issue with losing prime?
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DrAllis
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Posted: 31 Dec 2024 at 12:26pm |
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I know nothing about its system. There could be a pump just dedicated for steering and another for implement function. Either way, it sounds like it loses prime. I see an internet picture of the right side of the engine and there isn't a typical power steering pump that is gear driven on the engine. If your lift works fine, I still think it's a loss of prime to a pump dedicated to the power steering, which might be belt driven ??
Edited by DrAllis - 31 Dec 2024 at 3:12pm
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Coke-in-MN
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Joined: 12 Sep 2009
Location: Afton MN
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Posted: 28 Jan 2025 at 10:59pm |
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Is the steering fully hydraulic , or is there a mechanical link from wheel to tires ?
If fully hyd then suspect the unit attached to steering wheel valve body as part of problem .
On my TLB it's fully hydraulic with only a slave cylinder attached to the tie-rod under tractor ,
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Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something.
"Challenges are what make life interesting; overcoming them is what makes life meaningful."
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jpi72
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Location: Hudson, Iowa
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Posted: Yesterday at 6:10am |
The steering is fully hydraulic. As of now we do not suscept the pump. The forklift has one pump, and it feeds two systems. One system is the mast, and the other is the steering. What is a TLB? We blew a head gasket and expect the head back this week. Hopefully soon it will be fixed. Joel
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DiyDave
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Posted: 22 hours 4 minutes ago at 3:08pm |
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tractor loader backhoe...
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orangeman
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Joined: 12 Sep 2009
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Posted: 17 hours 23 minutes ago at 7:49pm |
jpi72 - can you post a picture of the 621 that you are working on? AC released and revised the 21' lift on a reversed D15 Farm Tractor, they also released and revised over time their 21' lift offering including an I- 60 with a 21' lift, and I-600 with a 21' lift and a later model referred to as a 621. AC Form TPL-554 is the Parts List for the Industrial 60, and Industrial 600 Fork lifts. It would be helpful to have that as a reference.
The steering cylinder attached to the axle used on the I-621 forklift has a supply and return line connected to an orbital motor or as AC refers to it a (power steering control valve) located at the bottom of the steering shaft. Without being able to see the unit I would guess that the return and supply lines could be leaking enough and possibly have leaked enough so that you have no remaining pressure to move the steering cylinder. What does fresh cardboard show when you leave it overnight underneath the steering shaft and the steering cylinder - any leakage?
What are the ambient temperatures where the unit is stored or parked? Is it freezing - I would guess also if the system has not been drained and refreshed that there is moisture in the system and perhaps has frozen and has turned to ice. If hydraulic supply is low you might not be making the necessary pressure to move the cylinder to allow "power steering" to work at all or even partially.
Also, if you have access, to the supply line you could plumb a T into the supply line and hook a pressure gauge into it to see what pressure you are carrying. Will check my AC library to see if I can find a pressure criteria for the 621 steering cylinder.
HTH's ~ Orangeman
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jpi72
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Location: Hudson, Iowa
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Posted: 4 hours 21 minutes ago at 8:51am |
Last summer I drained the hydraulic system and added new oil. The oil is not milky, so I doubt it is a moisture problem. I will put a cardboard under it when we get it running. You make a good suggestion that we have a leak in one of the lines. The problem seems to be worse in the wintertime. It usually happens the first start of the day and rarely after that during usage. I will try to reply when we get it running again. Waiting for the head to return from the machine shop. I will try to post a photo. It is a 160 cu. inch engine. Joel
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