Snowplow Hydraulics

[RodNH]

New to skid steers and new to the forum. I'm considering using an 8 ft Fischer snowplow from my truck on a Bobcat skid steer. The hydraulics on the Bobcat far exceed the capability of the truck and plow hydraulics. I need some kind of hydraulic interface arrangement that safely accommodates the plow equipment when mating it up to the Bobcat's hydraulics. I want to use the Bobcat's internal thumb-actuated external hydraulic control switch to angle the plow left and right. I don't want to modify the plow side as I want to be able to readily move the plow between truck and skid steer. The Bobcat's internal hydraulics will be used for lifting the plow using the Bobcat's lift arms. My first cut at this problem is shown in the diagram at the link below. I would appreciate any comments if this would work or not, or ideas if I should to look at other arrangements.
http://img64.imageshack.us/img64/1262/plowhyd2.jpg
Thanks,
Rod

 

[frogfarmer]

I use plain old flow restrictors on the angle feed lines. Got em from Surplus Center(Burden Sales) they are cheap and restrict both directions. They are just small orifice pipe nipples. I use one on both feed lines. The machine comes up to pressure and sends the extra oil past the releif valve of the unit. Works as it should and cost is very minimal. Your machine has all the over-pressure/over-volume safetys already built in. Use the same thing on my grapple bucket so it doesnt slam open and closed.

 

[Joe 396]

I use plain old flow restrictors on the angle feed lines. Got em from Surplus Center(Burden Sales) they are cheap and restrict both directions. They are just small orifice pipe nipples. I use one on both feed lines. The machine comes up to pressure and sends the extra oil past the releif valve of the unit. Works as it should and cost is very minimal. Your machine has all the over-pressure/over-volume safetys already built in. Use the same thing on my grapple bucket so it doesnt slam open and closed.

I'm setting up a plow right now. It's just an old 7.5' Western truck plow with hydraulics. I didn't even realize that I need to restrict the flow. Where would I get the flow restricters online?

 

[Joe 396]

I'm setting up a plow right now. It's just an old 7.5' Western truck plow with hydraulics. I didn't even realize that I need to restrict the flow. Where would I get the flow restricters online?

And you said you installed them on the angle feeds. What does that mean?

 

[skidsteer.ca]

And you said you installed them on the angle feeds. What does that mean?

att the quick couplers or cylinders, and they are available from www.surpluscenter.com
Ken

 

[Joe 396]

att the quick couplers or cylinders, and they are available from www.surpluscenter.com
Ken

Thanks for the link (I love this site). Which restricters did you get?

 

[RodNH]

Thanks for the link (I love this site). Which restricters did you get?

I decided to use adjustable restrictors so I can adjust the angle speed to suit. I do not want the plow to angle too rapidly, as it would using the Bobcat hydraulics w/o restrictors, even at idle speed. These are the restrictors I decided on:
https://www.surpluscenter.com/item.asp?item=9-5300-50&catname=hydraulic
I decided to reverse the restrictors from the position shown. Instead of restricting on the return, I think restricting on the supply with free flow on the return might be a better choice. There was no absolute need to use 1/2" restrictors for the plow but I am plumbing it all up for things other than just the Fisher plow and I want to have maximum flexibility. I decided to eliminate the cross-over relief valve due to frogfarmer's (and others) recommendations. I have not been able to determine the actual maximum recommended working pressure of the Fisher angle cylinders but judging from knock-off replacements, 2500 psig seems likely. The Bobcat's hydraulics relieve at 3500 psig, measured at the external hydraulics quick couplers. Since such a spike in pressure would normally occur only at the end of stroke of the angling cylinders, I'm counting on that amount of overpressure for very short periods to not be a problem. If anyone has any comments on that, please advise. I did find out that some fittings used by Fisher are brass that are rated for 1200 psig maximum working pressure. I'm not willing to stretch that to 3500 psig, even for short periods. It's easy enough to simply replace three 1/4" brass street elbows with high pressure steel hydraulic fittings.
I'm also planning on attaching the plow to the Bobcat using Bobcat's 3pt hitch adapter plate. The spread of the plow's A-frame is just right for meeting the Cat 1 hitch spread dimension. I am planning on using a chain top link, thereby permitting the plow to float about the hitch pins. I definitely want the plow to float like that. I do not like the idea of attaching the plow using the standard, rigid Bobcat quick-attach plate. That would only permit float via the Bobcat's main lift cylinders. That type of float probably does not work well for forward motion. It's intended for back-dragging. I suspect using it going forward would result in much digging in of the plow unless the ground is completely frozen. No pavement here.