Replacement Hydraulic Hoses for old backhoe

[aircommuter]

They have releif valves but the pressure goes through hose before it gets to the valve. Not only that the hoses loose strength over time especially on a backhoe where the boom swing works them so much. I have been making my own hoses since 1970 and I found that the 2 wire hoses last longer. Why save a little on 1 wire and change it more often. More down time too. You can get good life with one wire when the hoses are small diameter like #4, or 5 because they automatically have a higher pressure rating due to the smaller internal surface area.

 

[RickB]

Your industrial hoes prob have shock-relief valves on all the circuits to protect from that. Even my Bulgarian-made CUT hoe
has them on some of the circuits, including swing and boom. I would get hoses rated at least 500psi more than working
pressure.

500 psi above system pressure may not be enough to match circuit relief valve settings. Circuit relief is ALWAYS set higher than system pressure and one circuit relief may be different from another on the same valve body.

 

[aircommuter]

Exactly why the 2 wire hose is best, circuit reliefs are set to protect from the geometric leverage that can occur in multiple cylinder equipment like backhoes and knuckle booms.
The shock reliefs are often in the cylinder piston and do not come into play until the end of the travel. If one is setting a heavy concrete box or manhole he would want a hose failure.

 

[jclaudii]

So the -16 is the fitting size?

 

[UniversalHosman]

A couple of notes here from a late arrival: I cannot speak for other hose and fittings suppliers but we generally make our hose assemblies with 2-wire hose. This is because there is no significant savings between 1 and 2 wire and performance with 2 wire is better.

As far as the -16 goes, if you mean the "-16" in the OP's "3/4-16" - this refers to the thread size. While a -16 COULD refer to a fitting size - depending on the context - here it does not. As posted by DFKRUG, the fitting size in this case would be a 1/2" (sometimes called a -8).

Andy

 

[dfkrug]

500 psi above system pressure may not be enough to match circuit relief valve settings. Circuit relief is ALWAYS set higher than system pressure and one circuit relief may be different from another on the same valve body.

If, by "circuit relief", you mean the shock RV setting in a particular work circuit, then I would agree those are
set higher than the backhoe valve inlet RV. But maybe not higher than the system relief.

I said "working pressure" above, and that means any pressure the hoses would experience while working. If you
have a hoe RV set at say, 2500psi, and shock RVs in the 2600-2700psi range, a 3500psi WP rated hose may
be called for, esp if shock RV pressure levels are frequent.

 

[RickB]

If, by "circuit relief", you mean the shock RV setting in a particular work circuit, then I would agree those are
set higher than the backhoe valve inlet RV. But maybe not higher than the system relief.

I said "working pressure" above, and that means any pressure the hoses would experience while working. If you
have a hoe RV set at say, 2500psi, and shock RVs in the 2600-2700psi range, a 3500psi WP rated hose may
be called for, esp if shock RV pressure levels are frequent.

Circuit relief valves on the mobile equipment I am familiar with are ALWAYS set above the system relief. If not, the circuit relief setting will become the default working pressure for that circuit. The rest of your post quoted here is correct, including the semantic departures.

 

[CJONE]

You don't need to figure a safety factor into good quality hose. There is already a 4 to 1 burst factor in the hose. So if the circuit is a 3000psi then 3K hose is plenty. Now with equipment I always use at least 2 wire. If the outer cover gets damaged and the braid rusts on 1 wire it usually fails. With 2 or 4 wire there are remaining wire layers to keep the hose from failing. CJ
Oh and on the reuseable fittings, I only stock a few to get someone out of a bind and will not install them here at the shop anymore. So my advise is not to use them on new hoses, keep them for a emergency. The cost of a new fitting is not worth the headache of putting them back on a hose.

 

[dfkrug]

Circuit relief valves on the mobile equipment I am familiar with are ALWAYS set above the system relief. If not, the circuit relief setting will become the default working pressure for that circuit. The rest of your post quoted here is correct, including the semantic departures.

Semantic departure? From what? I have tried to avoid ambiguity in my terms.

Shock RV settings are going to be higher than the RV setting for the hoe valve. I said that. The "system RV" setting
is not necessarily the same as the implement setting, as detachable implements with their own valves may have
their own RVs. Those RVs are often set lower than the system RV. Industrial tractors with integrated hoes may
not use a separate RV in the hoe valve. I do not know the LONG 1199 unit, which I have stated.

As for choosing hoses with working pressure ratings, I said that I would choose a hose that is 500psi higher-rated
than my WP. I have no problem with using a hose that is rated right at the WP in some circumstances. The safety
factor is significant, as CJONE says. In my case, the WP is in the 2500psi range, and the quality of smaller hoses
with that low WP rating is not good enough for me.

 

[CCWKen]

If you go to a hydraulics/hose shop, they will charge you for the end fittings, the hose and the labor to build it. The last 1" x 5' suction hose I had made locally was $180! The two end fittings alone were $46 each. But they were the swivel type and unless you mess with a bunch of adaptors, pre-made hoses are not available. And I was glad to get it the same day too. You won't get that through mail order.