Blog

July 11, 2011

Jacking Bolts

By Stan Riddle

Jacking bolt for shaft alignmentJacking bolts provide a smoother, easier way of moving machinery than using pry bars and hammers. Their use will almost always speed up the shaft alignment process, prevent excessive minor moves back and forth, and generally make the task of shaft alignment much more pleasant.

So why aren’t they used more often?

  • Expense? Four pieces of threaded rod or bolts, with nuts welded to the base plate, make excellent jacking bolts.
  • Installation? Tack weld the nut to the base, and you’re done!
  • Too far from the jacking bolt to the motor? Use a spacer.
  • Can’t weld in that area? Drill and tap a metal block, and then drill and tap into the base. Bolt the block to the base.
  • Can’t do that either? Jacking bolt accessories are available from several companies, including VibrAlign!
  • Don’t have time? The time installing jacking bolts can usually be faster than the time chasing a motor back and forth with a dead blow hammer, not to mention repainting all the paint you beat off the motor.

Does this answer some of the questions in your facility?

Here are a few jacking bolt tips:

  • After the alignment is completed, back them off. Leaving the jacking bolts on the motor tend to bind the feet, increasing the chances of soft foot as well as the chance of warping the motor frame and increasing vibration.
  • When moving a machine horizontally, turn the bolt head one flat and notice the amount of change. This should give you an estimation of how many “flats” you need to turn to get the motor into the correct position.
  • Use the jacking bolt you are moving toward as a stop. Set the “gap” amount of movement with a shim or feeler gauge, and then “push” the motor with the opposing jacking bolt until it touches the jacking bolt you “gapped”. This will usually get you very close.
  • Use a laser alignment tool from VibrAlign and it can watch the move and you’ll know when you’re done!

5 Comments

  1. hamidreza on January 26, 2012 at 3:27 am

    Hi,
    If the motor was mounted on vertically or on a angular frames,then the jacking bolts should be left in place.This way you are not relying solely on the clamping(holding)force of your hardware to keep the motor secure,especially where possibility of vibration exists.
    Br
    Hamidreza



  2. Stan Riddle on January 26, 2012 at 7:20 am

    Jacking bolts can help in cases of vertical mounting, as long as the jacking bolts do not cause the feet to become deformed, or place undue stresses upon the motor frame.



  3. Nadeem Iqbal on February 12, 2013 at 2:09 pm

    Is there any hole in the foundation for jacking bolts, I think hole is only provided in pump skid for jacking bolts but not in the structure at which pump to be installed.



  4. Stan Riddle on February 12, 2013 at 6:49 pm

    Some pump companies provide jacking bolts. Others do not. I suppose you could specify that jacking bolts are provided. Or simply fabricate them yourself, if your company allows.



  5. Bhoopesh on April 17, 2018 at 1:34 am

    Is there any specific material/grade required for jack bolts?