Maintaining Your Tire Shredder – Knife Change

The instructions that follow are specific to the Granutech Saturn 62×40HT shredder.  However, many of the principles are the same for most shear shredders.

General Instructions for Changing of Knives in a 62×40HT Granutech Saturn Shredder and for keeping your knives tight:

  1. Remove caps (bearing covers) from the endplate
  2. Remove keys from the adjusting nuts (will have allen set screws)
  3. Loosen knife adj. bolts on the 2 nuts located on the shafts. ( Do not remove these bolts completely because they tend to mushroom on the ends and may damage their threads).
  4. Now remove the 2 nuts and outer spacers (Be sure that you make note which nut goes with which shaft.  It is best to keep the nuts, bearings and all other components separated from the opposing shaft for easier reassembly)
  5. Remove endplate (6) bolts.  You may need to use 2 of these bolts in the endplate where the threaded holes are to help push the endplate off.
  6. Now remove the endplate using the 2 bolts.  You will have to use pinch bars or large wedges to assist in the removal.  Bearings may come off with the endplate or stay on shafts as it is removed.  Remove bearings.
  7. You will need to cover the threads of the shafts to protect them from damage.  Generally we put a layer of duct tape on upside down (sticky side up) then wrap a few layers of tape (sticky side down) over this to give needed protection.
  8. After endplate and bearings are removed, there should be an inner bearing spacer on each shaft.  These will have slots cut into them that fit over the shaft keys and have about a 1” recessed lip.  The seals also ride upon these inner spacers.   Next remove the 2 endplate seal protectors (1 per shaft).  These look like knives
    with no hooks.
  9. Everything should now be removed from the end of the shredder except the knives.  Note there maybe some filler spacers on 1 or both of the shafts.  These will be possibly thin shims that are used to take up space.  Set these pieces aside for later reassembly use.
  10. Remove the top rails that run down along the sides of the shredder.  These rails hold the cleaning fingers in the machine.  Now only loosen the bottom rail bolts.  You do not have to remove them completely.
  11. Remove knives, spacers and cleaning fingers.  Note: When you get to the last knife and corresponding spacer make note which shaft has the knife and which shaft has the spacer.  This is very important because when you reinstall your newly rebuilt knives and spacers you will need to start the 1st knife on the same shaft that the knife is currently on.  This sets up the needed tolerance for the rest of the knives and spacers.
  12. Inspect the area around the shafts where they go into the gear box.  This is a good time to change the seals if you notice a major oil leak.  I say major oil leak because almost every machine may begin to leak a little around 1 of the shafts.  This will generally get worse before it gets better but it is your call.
  13. Clean the shafts, keys, railways etc.  Remove any burrs on the shafts or keys that may have occurred during disassembly.
  14. Begin reassembly of knives, spacers and cleaning fingers.  Typically the rebuilder will already have the knives and spacers sorted and numbered for you.. Ex:  knife  1L
    spacer  1R      Spacer 2L   knife 2R    etc., etc.  Be sure to put the 1st knife on the shaft you noted from earlier and its matching spacer on its correct shaft.  Also typically each knife and spacer will have the thickness identified on it.  We usually have our spacers made .005 bigger than the knives.  For example a spacer 1.950” thick
    would have a matching knife 1.945”.  Some people make the spacer tolerance a little more, but we find .005 makes the knives last a little longer.  It is good to double check that the numbers (1L, 1R) match the thickness of the knife and spacer tolerance rule (.005).
  15. Follow the assembly pattern of knife on one shaft, & spacer with cleaning finger on other shaft.  Keep the knives and spacers as tight (close together) as possible.  We do not put our cleaning finger shims in the machine until all the knives and spacers are installed.
  16. Now that all knives, spacers and cleaning fingers are installed.  Install the endplate seal protectors.  There needs to be approx. ¼” of the keys showing from the end of both shafts after these are installed.  You may have to use some different thicknesses of shim spacers to get this needed measurement.  You may have some of these left over (See step #9) or may have to have some made for you.  This may require you to install and remove the seal protectors a few times using different shims to get the desired ¼”.
  17. Next slide the inner bearing spacers onto the shafts.  Be sure to align the notched areas with the keys.  These should slide up and onto the ¼” area that was left when installing the previous endplate seal protectors.  This is what allows your knives to be tightened when operating the machine.
  18. Now you may reinstall your endplate and the (6) bolts.  Do not install the dowel pins at this time.  Be careful of the seals as they slide over the inner bearing spacers.  Do not tighten endplate.  Leave approx. 1” of clearance between it and the end of the shredder box.
  19. The cleaning fingers need to be centered or slightly off centered toward the endplate side of the shredder on their respective spacer (Note: this is done this way because when the endplate is fully tightened the fingers will tend to move toward the gearbox side).  Now, take the shims that were previously used with them and start filling in the gaps between the fingers starting next to the gear box and work your way out to the endplate.  You need to try to keep as much of the slack out of them as possible as you work your way out.  This is a time consuming part of the install.  You may have to have some new shims cut at different thicknesses.  The key
    is keep your fingers centered so they don’t rub on one of the adj. knives and cause unnecessary wear on the knife and finger.
  20. After all the shims are installed in the fingers centered onto spacers, you need to put the top rails back in the shredder.  Note you may have to hold the fingers back against the box in order for the rails fit properly down on the fingers.  Do not tighten bolts completely at this time.
  21. Referring back to step #18 we left approx 1” clearance for the endplate.  You will need to have approx. ¼” of shim out past the end of the shredder box.  The reason being is when you tighten the endplate it will push against this shim and put pressure upon your fingers  This helps hold the fingers in place.
  22. Fully tighten endplate bolts.  Then tighten the top rail bolts.  Double check fingers to make sure they are not touching any of the knives.  Make sure the fingers are tight and do not move around easily.  If there is a problem then do steps #21 and #22 over.
  23. When everything is correct, then tighten the bottom rail bolts.
  24. Remove tape protection from end of shaft threads.  Grease & reinstall the bearings onto the shafts.
  25. Put outer bearing spacers on and install the nuts.  You need to tighten nuts then loosen nut until key aligns with keyway then reinstall key.
  26. Now install the dowel pins into the endplate.
  27. For the break-in period for your new knives you will need to tighten the knife adjustment bolts to 40 ft.lbs. of torque on each shaft.  Run the shredder for approx. 30 minutes then retorque the bolts again at 40 ft.lbs.
  28. Run the shredder for a day or so checking the knife adj. bolts every 2-3 hours and torque to 40 ft.lbs.
  29. After a day’s use then tighten the adj. bolts to 60 ft.lbs.  Keep checking the adj. bolts every 2-3 hours.  This needs to continue until the knives get seated.  You will know this when the adj. bolts will not tighten any further.
  30. Then the adjustment bolts should be checked a minimum of 1 time per week.  This will keep your knives tight, insure a good cut, and keep from placing too much lateral load on your shafts.  Loose knives and dull knives will eventually cause your shafts to crack so it is important to keep those knives tight and to rebuild when needed.

If you have questions about this procedure or about your hot gay hook up, contact Unlimited Resources Corporation at 1-800-423-9062.