Sanderson 725c hydraulics

[Thecub]

Had a look

at a 725c today with a view to buying it. Anyway the guy said the hydraulics were a bit slow but had been sitting for a long time. So started it put the boom out and it wouldnt bring it back in. Also steering nearly locked solid. Boom wouldnt go up or down but crowd function worked slowly. Hydraulic oil looked clean enough. Any ideas on what might be the problem?

 

[MF-ANDY]

First port of call would be the suction filter in the tank. It's a metal strainer and can be washed.

 

[Mr Happy]

Start with getting the bus pump flow tested on the machine. Check the pump flow when under pressure when the oil is cold and again when it is at operating pressure. Also it does help if you have technical data so you know what readings you should be getting. The pump displacement is 42cc not sure on operating pressure.

 

[Thecub]

My thinking was their would be a valve to regulate between steering and boom functions that was somehow stuck. I didnt buy yet so trying to get a rough idea on possible causes at the moment.

 

[essexpete]

Where is Ace ?

 

[ACEngineering]

Where is Ace ?

At home havin a beer

 

[ACEngineering]

Had a look View attachment 780410 at a 725c today with a view to buying it. Anyway the guy said the hydraulics were a bit slow but had been sitting for a long time. So started it put the boom out and it wouldnt bring it back in. Also steering nearly locked solid. Boom wouldnt go up or down but crowd function worked slowly. Hydraulic oil looked clean enough. Any ideas on what might be the problem?

Very simple hyd system on a 725c. Nothing much to go wrong really.

Pump is probably worn out imo.
There is a priority valve for steering but it would only be stuck one way normally sending all flow to main hydraulics especially if machines been stored ages and with a bit of water in system.

That can normally be fixed by cleaning the spool. But thos problem sounds more like a lack of flow from pump either because its worn out most likely or the suction filter is blocked.

If it had been stood years unused I would have primed the hyd pump first on these by removing bung on suction pipe and a good slug of gear oil in there before starting.

You can try dropping the oil out and cleaning bottom of tank and suction filter first and then replace the pump. If auctions clean then it'll be pump cause theres nothing else.

Not the end of the world there still easy got.

 

[Thecub]

Thanks ace for that. Next question who stocks pumps for them or is it a common enough pump?

 

[Mr Happy]

Thanks ace for that. Next question who stocks pumps for them or is it a common enough pump?

It's not a common hyd pump it was made for Sanderson by Commercial Hydraulics. They can be repaired or new units are available.

 

[ACEngineering]

Thanks ace for that. Next question who stocks pumps for them or is it a common enough pump?

its a common enough pump, either I or @Mr Happy could source you one i'm sure.

 

[Mr Happy]

its a common enough pump, either I or @Mr Happy could source you one i'm sure.

What I meant is the pump was built for that manufacture only. Yes I can either repair or supply a new hyd pump.

 

[BredRedHfd]

First port of call would be the suction filter in the tank. It's a metal strainer and can be washed.

Definitely start here
,

 

[MF-ANDY]

Definitely start here
,

exactly! its an easy job and costs nothing.

 

[ACEngineering]

What I meant is the pump was built for that manufacture only. Yes I can either repair or supply a new hyd pump.

I know that but it's still easy got. Was lots built back in the day.

 

[Mr Happy]

I know that but it's still easy got. Was lots built back in the day.

Yes and I now know what you mean, different words means different things to different people [emoji3]

 

[Flat 10]

My thinking was their would be a valve to regulate between steering and boom functions that was somehow stuck. I didnt buy yet so trying to get a rough idea on possible causes at the moment.

You can take the valve out, clean it and put it back in. Its under the cover, behind the battery, square box like a fag packet. Don't loose the spring and remember which way round it goes. The suction filter WILL be clogged if its at all like our old 725, the ram seals degrade and let loads of 'fluff' into the system. Ours was so bad that the suction filter had cavitated and required a new one.

 

[Flat 10]

exactly! its an easy job and costs nothing.

If you have a long arm and a big spanner............

 

[ACEngineering]

You can take the valve out, clean it and put it back in. Its under the cover, behind the battery, square box like a fag packet. Don't loose the spring and remember which way round it goes. The suction filter WILL be clogged if its at all like our old 725, the ram seals degrade and let loads of 'fluff' into the system. Ours was so bad that the suction filter had cavitated and required a new one.

725c is a later machine with the non fluffy ram seals

 

[Thecub]

Think i will take a chance on it and see how i get on when i have it home. Thanks for all the feedback will keep everyone updated. Will definately have tank off first.

 

[Flat 10]

725c is a later machine with the non fluffy ram seals

Hallelujah