cross over relief for snow plow

[nybirdman]

I think I need to put a cross over relief on my FEL mounted snow plow.Anyone have a parts number and pipeing diagram.It is an old Curtis truck plow ,fairly new cylinders&hoses.

 

[J_J]

Do you need a single relief or a double relief.

1/2 NPT 16 GPM 1000-2500 PSI RELIEF VALVE

1/2 NPT 30 GPM 500-1500 PSI HYD CUSHION VALVE

 

[grsthegreat]

jj, my plow has a single cylinder. are you saying i can add one of these cushioning valves?? i always thought you need to have double, counter acting cylinders.??

 

[J_J]

grsthegreat ,

You mean that you only have one cyl to push and let the ground force retract/close the cyl.

A relief valve can be set up on just about hyd cyl to protect that cyl, when the valve is in neutral.

No you do not need a double relief for a single action cyl.

Some valves have work port relief.

My BH bucket spool has double work port reliefs.

 

[nybirdman]

I have two cylinders,one line to each cylinder.So single action?Again how to hook up.Thanks.

 

[PILOON]

Both cylinders are single action. The crossover valve protects the extended cylinder by dumping over to the retracted cyl side.
That system only protects the extended plow corner from collisions with stationary objects like curbs etc., but then when plowing your curb side is always retracted as you push snow to the curb.
They only work with dual single action cylinders.

Install is simple: 2 inlets and 2 outlets and generally 2 adjustments for pressure 'dump over'

The only time they worked for me was when I tried to break frozen snow banks with my extended plow tip, otherwise in 10 yrs of contract plowing they never acted.

 

[J_J]

Are you saying that you dump from one cyl to another cyl.

A single SA cyl only has one side. The other side is air.

 

[LD1]

Actually most SA plow cylinders, both sides are oil. The rod don't have seals, just a large ring that keeps it from coming out the end of the barrel.

Not sure what part you need, but I know they make them. You need to dump over pressurized fluid from one cylinder to the other and vice versa in event of catching something. On a truck mount unit, the crossover valve is an integral part of the PA block on the power unit.

 

[RickB]

Bailey hydraulics sells a crossover relief valve we install on plows that lack them. Crossover relief valves are effective on plows having one double acting cylinder or two single acting cylinders.

 

[LD1]

I have always wondered, but how well do they work on a single DA cylinder due to the difference in volumes of fluid between the rod side and the base side? I just assumed they wouldnt work well at all??

 

[PILOON]

Are you saying that you dump from one cyl to another cyl.

A single SA cyl only has one side. The other side is air.

Yes JJ, that is how those valves work. In effect they are more or less specific to snow plow type operations.
It would be like having 2 SA cyls connected together with one single hose, the movement of one will be replicated by the other and in effect can replace throttle cables (bowden).
PRV's usually have 3 ports, in/out and 3rd return to reservoir. In case of crossover rather than to tank it dumps to other s/a pressure line hence only 4 ports.

 

[grsthegreat]

grsthegreat ,

You mean that you only have one cyl to push and let the ground force retract/close the cyl.

A relief valve can be set up on just about hyd cyl to protect that cyl, when the valve is in neutral.

No you do not need a double relief for a single action cyl.

Some valves have work port relief.

My BH bucket spool has double work port reliefs.

JJ, no i have a single double acting valve to run the snow blade. It powers to retract and powers to extend. I see that some plows have twin cylinders that oppose each other...and im not sure if there single or double acting.

i was wondering if they make a cushion valve for a single double acting system

thanks

 

[RickB]

I have always wondered, but how well do they work on a single DA cylinder due to the difference in volumes of fluid between the rod side and the base side? I just assumed they wouldnt work well at all??

They work a whole lot better than not having one at all. Designing a plow with one double acting cylinder is a cost cutting deal. Dual single acting is a better design and used by most mainstream plow builders.

 

[glastron23]

you definitely need a cross over on the plow cylinders, a short curb and your looking for hoses.. cylinders ... blades ... loader arms... etc.. i use these units.. CRV08-20 Hydraulic Pressure Control Valve Jim
getting advice for snow plows from Florida is like getting advice for sunscreen from some one in Alaska!!! LOL

 

[Deerherd]

i was wondering if they make a cushion valve for a single double acting system

thanks

Here's a picture of my old HLA plow showing a cushion valve on an angled single cylinder. (It worked great and kept the blade closer to the tractor)

It looks like the same valve on my new plow, which is a dual cylinder. (second photo)

 

[grsthegreat]

Here's a picture of my old HLA plow showing a cushion valve on an angled single cylinder. (It worked great and kept the blade closer to the tractor)

It looks like the same valve on my new plow, which is a dual cylinder. (second photo)

View attachment 365137

View attachment 365138

ah... ok now i see whats involved. i can add something like that easily. And i do see how that would be cheap insurance for my expensive plow and loader.

 

[glastron23]

nice pic of a twin dual acting cylinder set up..

 

[LD1]

Come to think of it, my backhoe has a cushion valve similar to that second plow with 2 DA cylinders. To protect the lines when you have a heavy scoop and are swinging and go to stop. Without the valve, all of that energy has to be absorbed by the lines when the valve slams closed. The cushion protects that.

Not saying it don't help, but certainly works better with two cylinders as opposed to a single DA. Cause fluid volumes are equal with 2 cylinders.

 

[vtsnowedin]

you definitely need a cross over on the plow cylinders, a short curb and your looking for hoses.. cylinders ... blades ... loader arms... etc.. i use these units.. CRV08-20 Hydraulic Pressure Control Valve Jim
getting advice for snow plows from Florida is like getting advice for sunscreen from some one in Alaska!!! LOL

You don't think that anybody that made their living plowing snow ever retired to Florida?

 

[vtsnowedin]

View attachment 365138

I had to look at that setup a while to trace out what was going on with it. That must be a very snappy swing if any real volume comes in from the main pump.