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BT om. Speed reduction on lower fault?

Number of messages: 12

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uplift
lincoln, United Kingdom

Hi, has any body had any faults with the cab not slowing down when it reaches the bottom?

-------------------------
upliftuk@gmail*com (*=.)

Modified 4 Apr 2009 06:43 AM
by poster.

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uplift
lincoln, United Kingdom

I've checked the swipe switch near the bottom of the mast - ok.
The height encoder has been replaced! (does it need re-programing?)
the card has been tested on another truck - ok

-------------------------
upliftuk@gmail*com (*=.)

Posted 4 Apr 2009 06:46 AM

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powerlifter
united kingdom, United Kingdom

Hi uplift you dont have to programme the truck if you have fit a height encoder, you can try adjusting the prop valve potentiometer.
I once had probs with the directional valve that controls the soft opening/closing operation basically it obtains a smooth start and stop of the lift/lower motion and it wasnt centralising causing oil to pass through faster than it should rather than gradually. i hope this info helps.

-------------------------
A good engineer is a helpful engineer

Posted 5 Apr 2009 03:51 AM

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uplift
lincoln, United Kingdom

It's the new type valve bank (the square blue ones)

Do you mean the pot on the card?

The soft stop/start seems to be working correctly when operating with the lift lower switch. Just doesn't soft stop when reaching the bottom?
How does the truck soft stop at the bottom electrically or mechanically through the valves?
I’ve narrowed it down to mechanically but could be wrong.

-------------------------
upliftuk@gmail*com (*=.)

Posted 5 Apr 2009 05:40 AM

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powerlifter
united kingdom, United Kingdom

Hi uplift 1st of all how old is the machine? yes the pot is on the A5 card
The directional valves operates in pairs Y34/Y41 at fork lift/lowering and Y69/Y70 at cabin lift/lowering.
The valves are soft opening which means that the valve piston opens and reduces the oil flow gradually to obtain the smooth start/stop iv had it where the valve has been sticking and also if the chain has not been set properly. or due to lack of adjustment the chains need to be adjusted at regular intervals due to stretch and wear and adjusting should be performed in two stages to obtain the correct fork height above the floor the lifting dampers after adjustment should only be slightly compressed and the measurement should be 80/85mm between floor and forks.

-------------------------
A good engineer is a helpful engineer

Posted 5 Apr 2009 07:05 AM

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uplift
lincoln, United Kingdom

the truck is 1998.
the chains are correct.
the card has been tested on a different truck without the fault accuring.
the pot on the card makes no difference to the speed when adjusted.
the valves have been stripped and cleaned - fault still apparent.

it's got me baffled.

-------------------------
upliftuk@gmail*com (*=.)

Posted 8 Apr 2009 07:40 AM

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powerlifter
united kingdom, United Kingdom

Hi uplift, can i ask you if the directional valve as two solenoids or is there two single ones.

-------------------------
A good engineer is a helpful engineer

Posted 8 Apr 2009 07:53 AM

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uplift
lincoln, United Kingdom

its like you described above. 4 valves. 2 working together on cab and 2 for rhe forks.

-------------------------
upliftuk@gmail*com (*=.)

Posted 8 Apr 2009 07:55 AM

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powerlifter
united kingdom, United Kingdom

Hi uplift can i ask does the height indicator register when the cabin is lfting? Reason i ask this is because the card doesnt know at what height its at to control the soft start.
On the a5 card led 301 and 302 are the signal channels A and B for the soft start so im wondering if youve got a broken wire somewhere.

-------------------------
A good engineer is a helpful engineer

Modified 9 Apr 2009 06:26 AM
by poster.

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uplift
lincoln, United Kingdom

I've checked them and they flash as the cab raise's and lowers.
also i've checked the wiring from the height indicator to the the block conector at the back of the cab. (as i know these wire's are quite Vulnerable going over the mast rollers)
a friend of mine tested a om with the height indicator disconected and it still worked.

-------------------------
upliftuk@gmail*com (*=.)

Posted 10 Apr 2009 00:56 AM

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powerlifter
united kingdom, United Kingdom

Hi uplift, how lucky are you id love a problem like that on one of my trucks something good to get your teeth into. so let see so far youve changed the height encoder,check the swipe switch (how did you check this?) had the card tested on another truck (ok) the chains are adjusted corrected, the prop valve pot is ok as this is on the A5 card and thats been check on another machine, the leds are sending the signal and the card is receiving as youv said this has been check and is working ok, the valves have been stripped,cleaned,checked rebuilt correctly and the faults still there f u c k youv def got a prob.
so the way the it works is when you press the switch for cabin lowering A2 receives a voltage on the imput 204. A2 opens the directional valve Y69 and the lowering valve Y70,so the oil returns from the cylinders through the activated valve, the flow restrictor and the oil filter back to tank are you sure the flow restrictor in the valve is ok even though you have checked it sorry if that came over like i dont think youve checked it properly. I didnt mean it to.

-------------------------
A good engineer is a helpful engineer

Posted 10 Apr 2009 03:27 AM

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uplift
lincoln, United Kingdom

This will sound dodge, some of the work has been carried out by another engineer and I’m picking up from where he left. (good engineer tho)

The height encoder has been replaced with a working encoder.
A new swipe switch has been fitted
The card has been tested on a different truck and soft stop worked fine.
Valves stripped, cleaned and inspected.

My test:

Carried out continuity test on the wires from the encoder to the block connector in back of the truck. (As that loom tends to get put through its paces on the mast rollers)
Checked inputs from encoder to a5 card – flashing away merrily.
Checked input on card from swipe switch to a5 card –ok
Also swiped switch with magnet – error code appeared – ok
Inspected chains- slightly out but not enough to affect slow stop.
Stripped valve’s, inspected, cleaned. – springs + plungers seemed ok (could be wrong) – fault still apparent.
Swapped fork lift/lower valve for cab lift/lower valve – fault still apparent (I know this doesn’t mean any thing in the world of diagnosis lol)
The soft stop/start seemed ok when using the lift/lower button.

What controllers the soft stop when reaching bottom?

Does the height encoder? ( apparently when unplugged on a working truck it has no effect on soft stop)
Does the swipe switch?

What happens when it goes into slow reaching bottom mode? As the valves them self control the soft stop/start when being operated from the lift/lower button mechanically inside? (shape of plunger) Does the voltage drop to the lower solenoid
Does the voltage increase to the lift solenoid to slow it down?

I borrowed the manual for this truck and there is no mention of the soft stop at the bottom of the mast?

Would love a working truck to get info from. Lol, looks like a job card.

-------------------------
upliftuk@gmail*com (*=.)

Posted 10 Apr 2009 05:09 AM

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