Hoe

MossRoad · Jan 21, 2003

I spoke with Don at Power Trac while at lunch today. He said that he would run a back hoe off of the MAIN PTO, not the AUX PTO. He said the MAIN PTO has a full 8GPM and 2500PSI and I would get better response from the hoe hydraulics by running it off of the MAIN PTO. He also confirmed that the fluid circulates from the pump, through the valve and back into the tank when the MIAN PTO switch is in the off position. When it is in the on position, the solenoid kicks in and the fluid heads out the hose on the lift arm. If there is no attachment, which means no place for the pressure to go, the engine bogs and the relief cartridge kicks in and dumps it back into the tank. That’s why it is important to have an attachment on the MAIN PTO before flipping the switch; to protect the relief cartridge and pump.

He said that as long as the attachment has open center hydraulics and the plumbing can handle the 8GPM@2500PSI the relief cartridge should never kick in. So, this answers a lot of questions. Now, if I could only convince the CEO that we need a back hoe /w3tcompact/icons/laugh.gif/w3tcompact/icons/laugh.gif/w3tcompact/icons/laugh.gif. (I’ll tell you right now, that ain’t gonna happen for at least two years) /w3tcompact/icons/smile.gif

Anonymous Poster · Jan 21, 2003

Oh well I stand corrected - but I tell you - I would be the first to complain if it did not have enough power off the Aux PTO

-edm

MossRoad · Jan 21, 2003

I believe you, honestly /w3tcompact/icons/grin.gif

I'm glad to hear it has enough power to move the machine around on the AUX PTO. That means it is a mucho powerful machine /w3tcompact/icons/smile.gif I like that.

duane · Jan 21, 2003

My understanding of the hydraulic circuit is the same as you guys have discussed.

·Tandem gear pump, front gear set supplies the main PTO, rear gear set supplies the lift/tilt/aux circuit.
·Front gear set (8 + gpm) flows through a normally de-energized solenoid valve back to the main reservoir. When energized, it flows to the main PTO, if no attachment hooked up, it will lift the relief resulting in a lot of heat and stress/strain.
·Rear gear set (3 – 4 gpm) flows through open center steering valve and open center lift/tilt/aux circuit back to the reservoir.
·I recall that the main PTO circuit has a slightly higher relief valve setting. My concern over using the main PTO circuit would be the speed/sensitivity of the hydraulics, depending on the cylinder diameters. As we say up here, it would be “wicked” fast (tend to get you into trouble a little bit easier). The hydraulics of the lift/tilt are pretty quick with the lower flow rate. Usually hydraulic control valve diameters are based on flow capability. The higher the flowrate, the bigger the valve, the higher the cost. Higher pressure capabilities also drive up cost, but I think the two circuits are fairly close.

With the above hydraulic circuit, you can see why starting a frigid Power Trac takes some oomph! As soon as the starter turns, it’s moving thick oil in both gear pump circuits, as well as the charge pump for the transmission pump, along with the engine crankcase oil. Another saying for a cold night is a ‘3 dog night’, well it would be a ‘3 dog start’ for the Power Trac.

Duane

davesisk · Jan 21, 2003

Interesting post about the cold starting. Ya know, I've oftened wondered if it wouldn't have been a good idea to use something like a centrifugal clutch on the linkage between the engine and the pumps. That way, it would be disconnected from the pumps when the engine revs were low (like starting and idle), but connected at higher throttle settings. Of course, the centrifugal clutches used on, say, go-carts do wear pretty quickly, I suppose...

Dave

marrt · Jan 25, 2003

Well, I finally got a chance to call John at Cadplans. The bottom line is that the Cadplans 821 Hoe uses an open center continuous loop hydraulic design and will work fine with the PT400 series. In fact, John mentioned that some folks specifically use the Cadplans design so they can locate the engine and pump remotely to avoid the noise and exhaust. Also, one would need to run the PT at about ¾ throttle because the 821 only needs a 6 GPM flow. However, if one got very proficient with the Hoe, I imagine you could increase the throttle to get a quicker response. Cool.

John also mentioned that the kit would be about $2700 without the engine and pump. That’s a savings of about $800. I think the price is very reasonable considering the 821’s capabilities. So, with the savings resulting from using the PT’s hydraulics, I can buy a real nice welder. Double Cool.

davesisk · Jan 25, 2003

Marrt:

Sounds like a good plan. If you've got the sufficient tools (like a decent bandsaw and a pretty good drill press) I'd suggest buying your metal locally...I think you can get the materials you need for quite a bit less than the $2700 kit. (I have heard that the kits aren't always cut and drilled quite as accurately as you'd expect for the price, but I don't know that from experience.) You'll have to cut and drill the material, but that's part of the fun, right? Then you'll have more money left for an even better stick welder!

Dave

marrt · Jan 25, 2003

Well, I got a pretty good floor standing 16 speed drill press. Bought is at TSC for about $150. Appears to be the exact same castings as ones with "real" brand names costing $50 to $100 more. Even has the same orange handles as you find on Depot's store brand drills. Probably made by the same Chinese factory.

Don't have a metal cutting band saw yet. Grizzly and others have some starting at $200. Any recommendations. Also, do you know any place to get some decent metal drill bits cheap?

davesisk · Jan 26, 2003

My lovely wife gave me a metal cutting bandsaw for xmas. It's Harbor Freight's Central Machinery house brand...usually around $179-199, but you can get it for $139 on sale. Here's the url: <A target="_blank" HREF=http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=37151>http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=37151</A>. The legs are sheetmetal and kind of dinky, but the saw body is cast-iron and very rigid. It works very well, and makes really nice cuts! Run it at it's slowest speed with a blade that has a high TPI (teeth per inch). Beats the heck out of the 14" chop saw I have! No standing there getting showered in sparks, clamp the part in the vise, lower it and sit back while it cuts (now that's my kinda work!). Northern Tool has a similar one (probably made in the same Chinese factory too), so look both places for one on sale.

On the drill bits, Harbor Freight has a 29 piece set (up to 1/2") of Titanium Nitride coated bits for around $25 (great price). I've used my set for quite a while without significant dulling. Give that a look too...

Can you tell I like Harbor Freight? /w3tcompact/icons/smile.gif Mostly decent tools for a great price...can't beat that!

<font color=red>Oh, one more thing, email me at davesisk@ipass.net and I'll forward you a $10 off coupon...</font color=red>. On second thought, I'll just attach it to this post!

HTH,
Dave