Hydraulic thumb lock

[AdamsExcavating]

looking to purchase and or fabricate a lock for my hydraulic thumb to eliminate drift down. Looking for ideas, I like the patented lock rockland uses on their stick mounted thumbs and wondered if it would be possible to purchase that mechanism and fabricate onto my stick and thumb because I like the idea of not having to enter/exit the cab every time I want to utilize the thumb as we use it quite often. Thanks in advance!

 

[GregsHD]

Have you spent any time troubleshooting the cylinder drifting problem?

I wound be more keen on stopping the internal leakage rather than having an extra device to lock the thumb up.

 

[Wes J]

Sounds like you just need a huge detent spring. When you open the thumb fully, it snaps into the spring detent. The spring is strong enough to hold it from drifting, but not so strong the hydraulics cannot push it out.

 

[Bls repair]

Try turning the hydraulic on ,off valves to the cylinder off . If the cylinder leaks down,it is bypassing . If it doesn’t you can use them to hold the thumb . I have used the valves to adjust the speed of travel of the thumb by partially opening the valves.

 

[uffex]

Good day
I would be inclined to go towards Gregs suggestion installing a simple lock valve in the rod side of the circuit would resolve the issue.
Kind regards
Uffex

 

[AdamsExcavating]

The cylinder has drifted down since new. Where would I buy such a spring?

 

[John C.]

Thumb cylinders and thumbs are all made by after market manufacturers and are price sensitive. One of the places where money is saved is on the cost of the cylinders. Most that I've seen leak down when new and the failure rate is several times higher than an OE built cylinder.

What I have seen is a tab welded on the cylinder base mount that a locking pin can be inserted in to hold the thumb in the open position. That might be a little tight since yours is not a progressive linkage type thumb.