kubota b7800, bh75 hoe, adding hyd thumb

[agjones]

The working psi of your tractor is something like 2250 psi approaching 2x the working rating for the steel. It's expansion fatigue that is the enemy. Every time you exceed the working pressure of the steel, the burst pressure is reduced. The specs you cite are long-term vs instantaneous.

I find that the steel piped (as opposed to bent tube) circuits on older equipment I wind up with is a leaky mess bc the fit of the deformed thread pipe style just can't deal with the system and equipment motion vibration. Hose deals with that very well as do modern fittings like jic, orfs, orb.

If power beyond is not an option perhaps a flow divider (up stream of the existing valve) would solve the problem. Most of the cast iron dividers are rated for pressure on both the streams.

If you go that route, be sure you're still protecting the circuit with a pressure relief. Either in the divider or valve.

 

[agjones]

any suggestions on a correct valve 4 this? the valve i have is 4 port open center.

A lot of valves share a common size or two of power beyond sleeve. I've found surplus center and cross have both been helpful in identifying which valves can be used power beyond... They're not always labeled on the casting or diagram.

 

[agjones]

Yet another option is to use a selector valve to switch between the thumb and some other function. It's a compromise but quick and safe to install.

 

[garthr]

thanks to all for the info, advice, and safety concern.