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Genie TMZ34/19 Man Basket Jerks When the Up Button is Pressed

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chuckcastiglion

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Joined
Aug 25, 2013
Messages
21
Location
NW PA
TMZ34/19. S/N T3401-328. Electric Sch #ES0209 VIN #5D8AA19171R000328
Blue Boards with contactor were installed a few years ago. Batteries are good.
All functions of the lift work.
Problem: Each time the "Up" and "Any Speed" button are pressed for the man basket, the contactor pulls in, the pump motor starts and then the basket moves very quickly for a split second and bounces back. The initial impulse is hard enough to spill paint out of a bucket. Once the initial jerk is over, the basket moves as it should. If you stop after a short movement, it does the same thing if you start again. The other arms both work fine. The basket cylinder is single acting. The initial pulse from the pump extends the cylinder a 3 or 4 inches. The baskets swings out then returns and bounces a couple of times. It acts like there is air on the cap end of the cylinder that compresses easily and then it bounces. Help.....
 
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Engineer44

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Nov 30, 2017
Messages
60
Location
Portland
Chuck, did you find the cause of your jerking jib cylinder yet? If/when you do can you post the fix? I have the same machine, a year newer, also with blue boards. Would love to hear what you find.
Engineer44/Dave
 
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chuckcastiglion

Member
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Aug 25, 2013
Messages
21
Location
NW PA
I talked with a dealer and was told I had to bring it in. Genie use to have phone help, but now it's only for dealers.
There was a guy that went by VOODOO something that seemed to really know his stuff. I tried to contact him but never got a reply.
I was going to try and add a resistor in line with the control line to the motor controller. Maybe dropping the voltage a bit will slow the pump down?....
Let me know if you find anything out.
 
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Engineer44

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You’re right, it is possible there is air in the jib cylinder. The air would compress and once the pressure is great enough to overcome the static friction of the cylinder rod, the rod end would extend relatively quickly as the air would act like a spring. That also would account for the bounce. The hydraulic oil isn’t compressible so the cylinder should remain in tight control, even though it’s single acting. Have you tried fully extending and retracting the jib cylinder several times? Sometimes several full strokes will purge the air. If that doesn’t work, the cylinders on your machine all have an air bleeder on the end where the hydraulic hoses connect.
 
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chuckcastiglion

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Location
NW PA
My cylinder is single acting. It has one hose that connects to valve block at the cap end of the cylinder. There is no connwction on the rod end however there must be a breather. I can manuallt push my basket out with no resistance extending or retracting the rod. I would think that the valve is normally closed so the basket shouldnt move freely. With the cylinder retracted, basket down, i removed the valve and cycled the pump manually for a few seconds. No air, just tranny fluid came out. Can anyone explain the hydraulics? If the valve is closed, the basket shouldent be able to be pushed out easily.....
 
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chuckcastiglion

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Aug 25, 2013
Messages
21
Location
NW PA
Here is my hydraulic schematic. The jib control valve is normally closed and should be closed by back to back check balls. No oil will move thru the valve when power is off. According to the schematics, I shouldn't be able to manually push the jib basket because it would pull a vacuum, unless I'm missing something....
 

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Engineer44

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Location
Portland
I wish I could be more help but my machine is partially apart right now because I’m doing some cleaning and repainting so I can’t test for the bounce/jerking thing. But if it’s helpful I can tell you my jib cylinder is single acting like yours and I can grab the basket and move it in and out freely too when the macine is not powered. Like you, I would think that you would not be able to extend the rod freely unless fluid were allowed into the cylinder behind the piston. But I haven’t seen a diagram of the innards of that cylinder and perhaps the design allows for the rod to be manually extended independently of the “piston”. (Since it’s single acting and relies on gravity to retract.)
 
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chuckcastiglion

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Aug 25, 2013
Messages
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Location
NW PA
Ya... maybe the rod is not "connected to the piston. Ill set it up and manually extend the basket and block it up. Then turn machine on and push the "up" button. Maybe it's free floating on purpose, maybe it's broke?
 
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Engineer44

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Chuck, got a question for you. When my jib is fully retracted (all the way down) the jib comes to rest about a foot away from the base/frame of the lift. There’s a wear pad on the main base between the outrigger webs but the jib never comes anywhere near it when stowed. Is it supposed to? I don’t see how it could because there are phenolic stop blocks between the two jib booms that prevent it from lowering any further. When you tow your machine do you lash the jib/basket to the frame? Otherwise it seems like it would bounce up and down when towed. I know, sounds like a dumb question but I’ve only towed mine once (when I brought it home). I use it here on the property and haven’t needed to move it.
BTW, I looked at the rod end of my jib cylinder and I do not see any vents. There are set screws and holes for a spanner wrench to remove the gland nut. Like yours, I can lift the jib up and down freely when it’s not powered.

Engineer 44
Dave
 
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Engineer44

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Chuck, I noticed the newer relay based control system for the TMZ-34 has an adjustable pressure relief time delay setting that minimizes/eliminates an upward jib bounce that could happen if you were to command the jib to travel up immediately after a primary or secondary boom up. I don’t know if the green boards and blue boards had provisions to minimize this or if that was something that was discovered later in production and built into the latest control system. The pressure relif time delay is talked about in the installation instructions for the updated control system. Downloadable.
 
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chuckcastiglion

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Aug 25, 2013
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NW PA
When I press any one of the (3) movements, the pump motor starts, accelerates faster and then slows down. This takes place in about a second or two. My unit didn't jerk before. I'm wondering if the aftermarket DC controller may be the cause. There are definitely (3) different speeds, but the first second of any speed starts with a high pump rev. I haven't had any time to play with it. Free time is coming soon...
 
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Engineer44

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Chuck (or anyone else reading this) would you have the installation instructions for the #160431 contactor kit? I can’t find it as a download. I already have the contactor and I know I’ll need a pre-charge resistor and a diode across the coil. I’d like to see the official installation instructions to see the recommended placement, mounting, the control wiring for the relay, etc. thanx all.
 
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chuckcastiglion

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Aug 25, 2013
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Location
NW PA
Engineer44 said:
Chuck (or anyone else reading this) would you have the installation instructions for the #160431 contactor kit? I can’t find it as a download. I already have the contactor and I know I’ll need a pre-charge resistor and a diode across the coil. I’d like to see the official installation instructions to see the recommended placement, mounting, the control wiring for the relay, etc. thanx all.
Click to expand...
I think I have it. It may take a day to find.
 
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tractormech

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Feb 19, 2015
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florida
Is there a counterbalance valve on the jib cylinder? If the valve is set at too high of a pressure or is defective that would inhibit smooth starting. You might switch hoses on the jib cylinder to another valve in the bank and see if the problem goes away or follows you...that will eliminate the control valve and point you elsewhere. Do the hoses have any tees to operate in conjunction with another cylinder? Like auto level on telehandler forks. It sounds like a counterbalance valve issue. Check the parts manual and see if there's a counterbalance valve that's the same that you can "borrow" and see if it fixes the issue. Also at the beginning you said you changed the controller and the problem started-go there first. Is the voltage adjustable? get a meter and see what it's putting out. It may be set too high. Before you tear into the hydraulics check that first. good luck
 
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Engineer44

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Not an expert but I have the same machine. I believe there are three single-acting cylinders - primary boom, secondary boom, and jib, all T’d from the same oil supply. Each cylinder has its control valve integral at the base of the barrel. And each one has an orifice restriction that regulates/slows the downward travel.
 
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chuckcastiglion

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Aug 25, 2013
Messages
21
Location
NW PA


Here is video of jerking basket when the LOW SPEED button is pressed with Jib button.
I added a 75k ohm resistor in series with the signal wire to the DC motor controller which drops the voltage to about 1 VDC. The basket jerk is manageable now. The issue seems to be that there is no voltage ramp up at the start.
Is this ramp somehow adjustable on the board?
 
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03hdrk

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Aug 28, 2015
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125
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N TX
Not familiar with your machine. But you might check to see if there is a calibration procedure for the controls. Or a threshold adjustment for the high and low voltages sent to the valves.
 
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