Electric pallet jack drops too fast?

[richard newman]

My Yale MPB040E pallet jack drops WAY too fast with a load, bam!!! What could cause this? Fluid was low when I got it, topped it up, no change. Now I'm curious what actually determine the lowering speed, some sort of flow restrictor? Attaching parts diagram.

edit- changed pdf to jpeg

 

[BT Fabrication]

they all do that, its an electric solenoid thing. skid steers are the same way. this wasn't designed to reduce the return flow from the looks of it, normally you need a second solenoid to do it that has a small orafice to return to the tank.

 

[SteveEx30]

they all do that, its an electric solenoid thing. skid steers are the same way. this wasn't designed to reduce the return flow from the looks of it, normally you need a second solenoid to do it that has a small orafice to return to the tank

Even the manual ones.. atleast all the ones I've used.

 

[Strostkovy]

Looks single acting. If you want to reduce the lowering speed break the extend line on the lift cylinder and install a check valve and needle valve in parallel with eachother and in series with the line.

 

[DDoug]

When you topped it up, did you bleed the lift cylinder ?

 

[richard newman]

When you topped it up, did you bleed the lift cylinder ?

It's not a closed system, there's a breather. The manual says to remove air by cycling up and down a few times.

 

[richard newman]

Looks single acting. If you want to reduce the lowering speed break the extend line on the lift cylinder and install a check valve and needle valve in parallel with eachother and in series with the line.

Thanks, this seems like it would certainly work

But I'm convinced something is wrong, with a load of just 1000 lbs it comes down so fast the floor shakes. Don't remember anything like it when I rented one years ago.

 

[Strostkovy]

It's not a closed system, there's a breather. The manual says to remove air by cycling up and down a few times.

There can still be air trapped under the piston that can't get out. You may have to tip the jack and then lower it for the air to make it to the breather.

 

[DDoug]

It's not a closed system, there's a breather. The manual says to remove air by cycling up and down a few times.

I'm not an idiot, I have worked on other forklifts, How many have you ?
Seeing how you only want to quote the manual to me, I'm done trying to help you.

 

[richard newman]

I'm not an idiot, I have worked on other forklifts, How many have you ?
Seeing how you only want to quote the manual to me, I'm done trying to help you.

Kind testy today Doug? I never said or implied that you're an idiot, that's not my style. Lighten up

 

[richard newman]

Problem solved!

Took the solenoid/valve assembly out, and found what looked like a flow restrictor inside. Marked with a red arrow on the drawing. Hole was .080", made one with a .040", made a huge difference!

Thanks for all the suggestions. Sure glad I didn't have to turn the jack upside down to bleed the cylinder, but I don't understand how just raising and lowering a few times does that?