Page 1 of 2 12 LastLast
Results 1 to 10 of 13
  1. #1
    New Member
    Join Date
    Jan 2013
    Posts
    14
    Location
    MT
    Tractor
    None yet

    Default Valve to control hydraulic motor

    I have an old skid steer (Bobcat 610) It is belt drive with 4 clutches. The clutches are getting worn and I would prefer not to replace all of them since it would be more than I paid for the skidsteer.
    I am considering connecting a hydraulic motor to the drive system on each side and bypassing the old drive system completely, this would also allow me to use a variety of engines if mine ever needs replaced.
    I know that ideally I would get a hydrstatic pump, or variable displacement pump. However, this is a project to SAVE money, not spend it.
    I already have several gear pumps and a vane pump that I have salvaged from other machinery. I also have several matching spool valves (Gresen 400).

    Question:
    Can I use regular spool valves or do I need something with a variable control in order to get fairly smooth operation? What would you recommend? I am just afraid it will be stop or full speed with these valves and was hoping for opinions.

    Remember, this is a 40 year old machine, so I'm not expecting it to operate like a cadillac, just functionality and safety.

  2. #2
    Super Star Member J_J's Avatar
    Join Date
    Sep 2003
    Posts
    17,362
    Location
    JACKSONVILLE, FL
    Tractor
    Power-Trac 1445, KUBOTA B-9200HST

    Default Re: Valve to control hydraulic motor

    There are motor spool valves such as these.

    20 GAL motor valve @3000 psi

    Surplus Center - 1 SPOOL 20 GPM PRINCE RD-2575-M4-EDA1 MOTOR VALVE
    J.J.

    When I works, I works hard. When I sits and thinks, I goes to sleep.

    Git er done.

  3. #3
    New Member
    Join Date
    Jan 2013
    Posts
    14
    Location
    MT
    Tractor
    None yet

    Default Re: Valve to control hydraulic motor

    Any idea how the flow control would be with those valves? How jerky? I see that they can be open or closed center. Does that mean I could make it hold/brake the motor when the valve is in center like a hydrostatic?

  4. #4
    Super Star Member
    Join Date
    Mar 2008
    Posts
    10,593
    Location
    Northern Fingerlakes region of NY, USA
    Tractor
    Kubota L3830GST, B7500HST, BX2660

    Default Re: Valve to control hydraulic motor

    Quote Originally Posted by J_J View Post
    There are motor spool valves such as these.
    20 GAL motor valve @3000 psi
    Surplus Center - 1 SPOOL 20 GPM PRINCE RD-2575-M4-EDA1 MOTOR VALVE
    I dont know that I would use a motor spool valve for a wheel motor drive as that would allow the machine to freewheel when not "in gear" (so to speak).

    Any thoughts?

    Aaron Z
    A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
    Robert Heinlein, Time Enough for Love

  5. #5
    New Member
    Join Date
    Jan 2013
    Posts
    14
    Location
    MT
    Tractor
    None yet

    Default Re: Valve to control hydraulic motor

    If I understand correctly, A regular spool valve (not motor spool valve) will not allow the motor to freewheel? Is it correct that motor spool valves essentially have a float between the two lines when it is in center position?

  6. #6
    Super Star Member J_J's Avatar
    Join Date
    Sep 2003
    Posts
    17,362
    Location
    JACKSONVILLE, FL
    Tractor
    Power-Trac 1445, KUBOTA B-9200HST

    Default Re: Valve to control hydraulic motor

    That is true.

    You could use an open cyl spool valve, but it would be jerky. When you released the valve it would stop/brake.

    Your best bet is a hydrostatic transmission for smooth operation.

    What size engine is in your machine?
    J.J.

    When I works, I works hard. When I sits and thinks, I goes to sleep.

    Git er done.

  7. #7
    Super Star Member
    Join Date
    Mar 2008
    Posts
    10,593
    Location
    Northern Fingerlakes region of NY, USA
    Tractor
    Kubota L3830GST, B7500HST, BX2660

    Default Re: Valve to control hydraulic motor

    Quote Originally Posted by J_J View Post
    That is true.
    You could use an open cyl spool valve, but it would be jerky. When you released the valve it would stop/brake.
    Your best bet is a hydrostatic transmission for smooth operation.
    What if you put in a crossover relief valve such as Surplus Center - 1/2 NPT 30 GPM 1500-3000 PSI HYD CUSHION VALVE or Surplus Center - 3/4 NPT 30 GPM 1500-3000 PSI HYD CUSHION VALVE with a spool valve. That would allow it to "coast" to a stop but would slow/prevent creeping when in "neutral".

    Aaron Z
    A human being should be able to change a diaper, plan an invasion, butcher a hog, conn a ship, design a building, write a sonnet, balance accounts, build a wall, set a bone, comfort the dying, take orders, give orders, cooperate, act alone, solve equations, analyze a new problem, pitch manure, program a computer, cook a tasty meal, fight efficiently, die gallantly. Specialization is for insects.
    Robert Heinlein, Time Enough for Love

  8. #8
    New Member
    Join Date
    Jan 2013
    Posts
    14
    Location
    MT
    Tractor
    None yet

    Default Re: Valve to control hydraulic motor

    Would I need one of those in each line (two lines per motor)? That would mean four of those little suckers if I only used two pumps.

    The engine is 30 HP.

  9. #9
    Elite Member
    Join Date
    Jan 2010
    Posts
    2,635
    Location
    Northern, IL
    Tractor
    Branson 2400H

    Default Re: Valve to control hydraulic motor

    Popeye,
    How smooth you start and stop depends some on the valve metering capabilities and some on the operator. If you move the valve to fast you will get sudden changes in flow.

    Another problem you will have is load changes on the drive motors will potentially radically change the motor speed since these valves are not pressure compensated. More expensive mobile valves have pressure compensation for each valve section and typically better metering characteristics. I.e. Rexroth M4-12 , Sauer Danfoss PVG, etc.

    I suspect you will also discover that your tractive effort (ability to do work) will decrease by 15% or more Vs the belt drive.
    Artificial Intelligence will never overcome natural stupidity.

    Branson 2400H MMM & FEL

    JD 112

    BX1850 gone but not forgotten

  10. #10
    New Member
    Join Date
    Jan 2013
    Posts
    14
    Location
    MT
    Tractor
    None yet

    Default Re: Valve to control hydraulic motor

    oldnslo,
    Thanks for the insight on that. I imagine that without spending a lot of money (almost enough to upgrade to another skidsteer), that the controls will take some getting used to.
    Good point on the loss of power due to efficiency, I will have to really think this through.

Page 1 of 2 12 LastLast

Similar Threads

  1. Running a Hydraulic Motor - Valve Question
    By ddivinia in forum Hydraulics
    Replies: 37
    Last Post: 01-14-2014, 07:49 PM
  2. Solenoid motor control valve
    By m7040 in forum Kubota Owning/Operating
    Replies: 2
    Last Post: 04-24-2007, 09:18 PM
  3. Hydraulic motor spool valve question
    By Wally01 in forum Kubota Owning/Operating
    Replies: 1
    Last Post: 11-25-2006, 03:28 PM
  4. Hydraulic Control Valve, T or P?
    By pekabu in forum Hydraulics
    Replies: 7
    Last Post: 11-25-2004, 09:18 AM
  5. Hydraulic Control Valve, T or P?
    By pekabu in forum Build-It Yourself
    Replies: 7
    Last Post: 11-25-2004, 09:18 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
© 2014 TractorByNet.com. TractorByNet is a registered trademark of IMC Digital Universe, Inc. Other trademarks on this page are the property of their respective owners.