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  • Users: hydromech
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  1. hydromech

    Complex Hydraulic Synchronising Problem

    As a bench mark, a Slack and Parr flow divider gave a position differential of 3% across 2 cylinders at 18MPa and stroke range of 1800mm. I couldn't get a better performance from any other device, but I could have paid more to have gears ground to match the housing to minimise the clearance...
  2. hydromech

    Complex Hydraulic Synchronising Problem

    Peter, It's not technophobia, it's balanced and free advice based on experience. I for one do not have a company to promote, in particular a company that has much to gain in advocating electronic control. I am fully aware of the full benefits of PID control with proportional or servo...
  3. hydromech

    Complex Hydraulic Synchronising Problem

    The divine truth... Thanks to the peace negotiator call Mr Mike Halloran... Have a star!!!
  4. hydromech

    Complex Hydraulic Synchronising Problem

    Can people not read...? My opening comment was to state that, from experience of both options and from the info given...a flow divider gives the most cost effective solution to the apparent problem. It was a piece of balanced advice. My objection to Peter's approach was that it came late on is...
  5. hydromech

    Complex Hydraulic Synchronising Problem

    It's this sort of activity that makes me want to stop my contribution to this forum. I give honest and open support and ideas based on real experiences to give a cost effective and robust solution to a problem. Peter, it is not appreciated when you give advice that contradicts and undermines...
  6. hydromech

    Complex Hydraulic Synchronising Problem

    The over centre valve holds the oil in the cylinder, there will be no leakage across the spool. You don't need the PO checks, they are not doing anything. The divider will only leak when it's operating. To reiterate, the over centre valves will stop the oil coming out of the cylinder so the...
  7. hydromech

    Complex Hydraulic Synchronising Problem

    Go with that then...if the cylinders are mechanically linked, there will be no problem. If you use a decent flow divider, you'll get good performance out of it. Your schematic shows proportional directional control valves, that would be proper expensive. Do you need accurate position control...
  8. hydromech

    Complex Hydraulic Synchronising Problem

    Yes I did see the link... There are good reasons for using 4 DCVs. 1) It gives you synchronised flow in both directions 2) It means that you don't have to use the flow divider as a flow combiner, the tank lines from the DCVs go around the flow divider. 3) When using as a flow combiner, if...
  9. hydromech

    Complex Hydraulic Synchronising Problem

    From experience of servo and proportional controls V flow divider...I would suggest going for a flow divider. Use 1 flow divider...ideally from Slack and Parr in the UK. Use a directional control valve for each cylinder that you want to operate. If you want to drive 4 cylinders, use a four...
  10. hydromech

    low speed response

    You can start by posting the question in the correct forum...Solid Works...Pro Engineer...AutoCAD...Inventor. Then you need to look at a better machine, or a better network speed...or both
  11. hydromech

    Pd Rotery Screw Pump pressure vs flow

    The actual flow is a function of the volumetric efficiency. A sensible pump manufacturer will quote the flow rates at the maximum working pressure with the stated volumetric efficiency. As the pressure in the pump increases, oil leaks through the clearances between the screws and housing...
  12. hydromech

    Axial piston pump design

    I have placed a call with Bosch Rexroth HQ in the UK. They are stumped at the moment, but have promised to let me know when they find out. A point to note...They said that they only change the port plate to convert a pump to a motor. Just to increase efficiency. A motor inlet pressure will be...
  13. hydromech

    Hydraulic hoses - Metric vs BSP pro's and con's

    I always tended towards metric hose ends because it is much easier to adapt between flexible and rigid tubing. It reduces the number of potential leak paths. Other than there is not much in it. Neither is being phased out as far as I understand. The pressure limitations on both are comparable...
  14. hydromech

    Axial piston pump design

    I tried asking several people from Bosch Rexroth...they don't know either. There will be a select few in Germany that know for sure, but they never answer the phone.
  15. hydromech

    Axial piston pump design

    Dudmac... I feel that you are missing the point a little on this one. The question posed was in relation to a Bosch Rexroth bent axis piston pump. These pumps are unique in that they have a maximum specified inlet pressure. There many other similar pumps that operate in the same manner, both...
  16. hydromech

    Axial piston pump design

    It's been ages since I saw that book...very informative it was. I've tried really hard to think why they would want to limit the inlet pressure, there is just no obvious explanation for it other than the sealing. Only one other thought... Perhaps they have balanced the rotating group to...
  17. hydromech

    Axial piston pump design

    It's perhaps a little unprofessional to say this, but that is rubbish. Any and all pistons that see inlet pressure will see outlet pressure too. How can you say that excessive force applied when the piston chamber is filling is more damaging than when the piston chamber is being emptied with...
  18. hydromech

    Axial piston pump design

    Indeed, there are different types of axial piston pumps. The pumps in question don't have any valves, but some do.
  19. hydromech

    Axial piston pump design

    No, they don't have any valves in them. I'll leave you to check how port plate piston pumps operate. Google it...!!!
  20. hydromech

    Axial piston pump design

    These are port plate piston pumps, they have no valves in them. The pumping action is a function of the reciprocal motion of the pistons as they follow the angle of the swash. Any pump will benefit from high inlet pressure. I still can't see that the pressure limitation on the inlet is anything...

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