Snow Attachments Hydraulic conversion of a PTO snow blower

[drmac]

Like others my neck is no longer up to the æ–—etç—´ drive backwards to blow the snow thing (mine is 76 years old) and I had an old PTO driven blower. Having just updated to a DK50 Cab tractor I faced the question of how to put the blower on the front.

Without going into all the reasoning my decisions were:

1. Use a 20gpm hydraulic pump on the PTO to handle the 35-40 HP my Woods 74 snow blower requires.
2. Feed it from a 25gal fluid reservoir to follow the å*µallon per gallon rule of thumb for fluid cooling.
3. Drive the blower with a 540rpm hydraulic motor matching the 35-40 HP requirment.
4. Plumb the system with ï½¾ inch hoses to avoid flow restrictions.
5. Protect the pump and motor with a pressure relief valve.
6. Drive the chute rotator with a little gear-head 12V motor.
7. Blow snow in air-conditioned comfort!

My parts list is (the part numbers are from Central Surplus, who gave me great service):

9-1047-1-C pump
9-6666 torque bar
9-6135-75-L relief valve
9-7950 reservoir
9-7290-125 internal tank strainer
9-059-10 10 micron filter
9-072-1063 motor
1-1563-G shaft coupler
5-1726 20rpm 12V gear-motor
11-3259 DPDT switch
1-3421-E coupling half
1-3421-M coupling half
1-3421-X coupling insert
4?-7700 ï½¾ inch Gates quick couplers
1?-7290-125 tank strainer
1?-4404-20-20 adapter
2?-5404-12-12 nipple
1?-6815-16-16 elbow
3?-6806-12-12 elbow
2?-078-240 ï½¾ inch 20 foot hose
4feet?-1956 1 ï½¼ inch return hose
locally supplied 30 inch relief valve return hose
wire, zip-ties
quick change plate for the FEL
miscellaneous steel

I designed the fluid reservoir support for the 3-point, the QC plate attachment and gusseting, the hydraulic motor mount and the chute motor housing and had the welding done locally.

Thus far the conversion was tested with our first 8 inch snowfall two weeks ago and performed flawlessly.

My total cost came to $3186 (welding was $750 of that) including the 20 gallons of fluid to fill it.

I think I earned an A in Hydraulics 101!

 

[nybirdman]

Nice job;probably saved your-self $10,000 or so.A total new unit like that is about $15,000.What's nice now you can add other front mounted implements if you desire.No snow to speak of here in norhern NY,I just mounted my front snow plow/rear blade combo.

 

[oldnslo]

Nice job, One item you might want to consider if you haven't already, is a check valve between the inlet and tank ports on your motor to allow it to free wheel down without the potential of cavitation.

Here is link to an example of one.

https://www.surpluscenter.com/item.asp?item=9-7933-12-65&catname=

 

[drmac]

Thanks for the kind words, guys. Educate me (I'm now in Hydraulics 102). On my Kioti I'm not using any control valve for the snowblower, just engaging the PTO at idle and ramping up to engine speed before moving into the snow. When finished I stop, give it a little time to clear the auger and chute, back down to idle and only then disengage the PTO. Are you thinking I have a significant risk of cavitation and possible hydraulic motor damage when using this technique?
I appreciate your experience and wisdom.

DrMac

 

[oldnslo]

Thanks for the kind words, guys. Educate me (I'm now in Hydraulics 102). On my Kioti I'm not using any control valve for the snowblower, just engaging the PTO at idle and ramping up to engine speed before moving into the snow. When finished I stop, give it a little time to clear the auger and chute, back down to idle and only then disengage the PTO. Are you thinking I have a significant risk of cavitation and possible hydraulic motor damage when using this technique?
I appreciate your experience and wisdom.

DrMac

DrMac,

Since you are idling the tractor down there is less risk. Does the blower keep spinning for a few seconds after you shut the PTO off? If yes you are potentially cavitating the motor from the inertial force of the snow blower fan.

When idling the tractor down does the blower slow down at the same speed as the tractor? Here again, depending on how fast you you change engine RPM and how much inertial load their is on the motor it might be border line cavitation.

NOTE: I tend to be overly cautious and try to design for worst case.

Roy

I would say you are past hydraulics 102..

 

[drmac]

Roy, thanks for your thoughts and pardon my delay in getting back to the machine. With my tractor in it's house at about 57 degrees the auger appears to slow down at about the rate of the engine, which I do not do abruptly. When I disengage the PTO the fan stops in about half a revolution. Strikes me as no significant inertial back-pressure on the hydraulic motor.

"The best case is cheap--the worst case costs a lot!"

Thanks again, DrMac

 

[Jesse11]

Great job,thank you for your skills:thumbsup:

 

[JohninCT]

Wow! nice job. Please report back when you get more use on how it is working. Let it snow :laughing:

 

[drmac]

Still no snow here, but a little followup.

Along with checking for inertial back-pressure in the hydraulic system as Roy mentioned and getting ready to install the fan modification kit I got from Clarence I discovered fan run-out. I mean REAL fan run-out. My estimate is about 17 thousandths, that would be 17 thousandths of a YARD (yes a yard, the distance from the King's nose to his outstretched thumb)!!!

Apparently in its previous life it vomited up a very big rock and bent the transmission through-shaft. It was still blowing snow three weeks ago but now I know what I'll be doing this summer! I'll be back to you on that project later.

DrMac

 

[rbargeron]

Hey DrMac - very nice looking job - design and execution look very professional. Nothing teaches hydraulics like putting a system together. On the question of spin-down inertia, a little cavitation in the system for brief periods won't do any harm. Cavitation is bad if it's constant. The few times you might pull bubbles on slow-down won't have any measurable effect. Regarding engagement, a control valve can be handy but isn't really necessary. On gear-and-shaft drives from the rear pto (Erskine and Lorenz), engagement is all by pto clutch.
Thanks for posting a great project! Take care, Dick B