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Help with Hyster H7.00XL steering problem

Number of messages: 8

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t_lift
dubai, United Arab Emirates

HI was wondering if anyone can help me,

Got a 7 ton hyster , while driving when the steering wheel is turned there are occasions that the tires do not follow suit, we then have to steer in the opposite direction to correct it. This is a big problem as when the machine is operated with load, we find that when we turn, the machine keeps going straight. In saying that it happens 3 times out of 50 turns.

We replaced the steering pump and checked everything but still cant find the problem.

Any ideas guys ?

Posted 24 Feb 2009 06:26 PM

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proshadetree
Tennessee, United States

Ive had this problem with the s70 ft and the s40xm. It was the packing in the steer sylinder both times.It the steer unit was unloaded by jacking up the rear of truck you couldnt make it fail the more weight or rear of truck the more it failed.I found by taking 1 hose off at full cut.The low side of that cut and see if it bypasses.Messy way to see but it works.

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"Work leads to profit, mere talk leads to poverty"

Posted 24 Feb 2009 11:11 PM

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kevin_k
dumfriesshire, United Kingdom

definately seal bypassing in the steer cylinder . seen it many a time

Posted 25 Feb 2009 04:20 AM

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jan_j
Ned antillen, Netherlands Antilles

If the seals steering cylinder are oke, the only possibility can be the steering flow divider,
If the steering flow divider fails there is your problem.
On of the most comment problems is a leak of oil quality I advice to renew at first the hydraulic oil before you will exchange any part.

Posted 25 Feb 2009 06:33 AM

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t_lift
dubai, United Arab Emirates

Thanks guys, ....... will check the steering pump again...

Posted 25 Feb 2009 07:06 PM

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tugmaster
United Kingdom

no flow divider on a h7.00xl.separate steer pump. defo steer cylinder seals.

Posted 26 Feb 2009 03:30 AM

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jan_j
Ned antillen, Netherlands Antilles

The steering control unit is a rotary valve that controls the movement of the steering cylinder. The supply of oil for the unit comes from the steering hydraulic pump. The control unit has a minimum restriction to oil flow when the steering wheel is not moved. The control unit has four ports. A manifold block is installed on the steering control unit over the four ports. The inlet port in the manifold block has a check valve (steering control valve) and a relief valve and is connected to the hydraulic pump. The relief valve is set at 11.7 to 12.4 MPa (1700 to 1800 psi). Two of the ports are connected to the steering cylinder. The port for the drain circuit is connected to the inlet of the brake valve. All of the oil that flows to the steering control unit flows to the brake valve.

Posted 26 Feb 2009 05:58 AM

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tugmaster
United Kingdom

yeah i got you jan. my appologies.i thought you thought there was a flow divider in the hydraulic pump, like a steer priority valve.

Posted 26 Feb 2009 08:25 AM

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