wheel loader lift high speed only

[maxpax]

Hi.

I am close to buying a chinese changlin zlm15b from around 2008. The loader on it is a bit annoying when lifting, it's not possible to lift slowly by pulling the lever a little bit, pulling it and coming 'bout half way suddenly it jerks up in high speed. Same with raising the tilt. However, when lowering the loader (and/or tilt) it's perfectly controllable and possible to lower slowly och fast by choice. Everything else in the hydraulics works good.

So, the question for people who are experienced with hydraulics is what comes to mind first? I have just started to learn about hydraulics and my thought would be maybe a wrongly mounted flow control valve or something. Any ideas on how to achieve a controlled lifting motion?

/MaxPax

 

[bigdeano]

My guess would be the valve is not made correctly to allow for feathering smoothly. When you move the valve a little bit, before it starts lifting, does it sound like it's loading the pump? I have one valve that blocks the pump flow before it opens the port to the cylinder, so it's all or nothing to the cylinder.

You could try reversing the hoses to the cylinder to see if it lifts smoothly. If it does that would eliminate any other problem in the system.

Some valves just aren't made very well.

 

[maxpax]

Thanks for the answer!

As I remember now it doesnt sound like the pump get loaded before, but the whole machine has quite much sound to it so the sound from the hydraulic pump might be drowned by the engine and loose plates. I will definitely try to swap the hoses if (when) I buy it and get it home.

 

[oldnslo]

Does the loader stay up once raised or does it drift back down? Only been around one chinese wheel load and the valves on it were very poor quality. Wouldn't feather very well, allowed the loader to drift down very rapidly, etc.

 

[maxpax]

It does not drift down at all.

 

[oldnslo]

Can you tell if the valve is controlled via mechanical linkage, hydraulic pilot joy stick, electric proportional. Hydraulic pilot and proportional could have a control issue causing the problem

 

[maxpax]

Can you tell if the valve is controlled via mechanical linkage, hydraulic pilot joy stick, electric proportional. Hydraulic pilot and proportional could have a control issue causing the problem

Yes.

The valves are right in the cabin and there are two levers with one function each. I have not got the machine home yet, that might be in august...

 

[maxpax]

Okay. Now I have the machine at home. I work a lot now so I'll check things more closely in the weekend coming or next week when work will not be so intense.

However, I moved it today and tried that which my friend the gravel-delivery-guy told me, to rev up the engine when working the lift/tilt. It kinda worked and not at the same time. The tilt could be slowly lifted with higher rpm, very nice! But - the boom arms or whatyacallit doesnt allow feathering even with high rpm. There's a pssss sound coming before the jerk so maybe it's the problem that bigdeano talked about...

 

[CincyFlyer]

Okay. Now I have the machine at home. I work a lot now so I'll check things more closely in the weekend coming or next week when work will not be so intense.

However, I moved it today and tried that which my friend the gravel-delivery-guy told me, to rev up the engine when working the lift/tilt. It kinda worked and not at the same time. The tilt could be slowly lifted with higher rpm, very nice! But - the boom arms or whatyacallit doesnt allow feathering even with high rpm. There's a pssss sound coming before the jerk so maybe it's the problem that bigdeano talked about...

They must use the same loader valves that Mahindra uses on some of their loaders. Does it say Besko on the valve? I'm replacing mine (to add a grapple function.)

 

[maxpax]

Now I removed the cover from the valves and took some pictures: