We have been selling Ro-Tap Sieve Shakers for over 80 years. Our sieve shakers are known all over the globe as reliable particle size equipment.
The thing about the Ro-Tap is that it’s made up of different parts and pieces that all work together to give you consistent results. If you are someone who uses our Ro-Tap, you probably know that maintenance is required.
In this article, we are going to give you instructions on how to replace 6 of the most commonly replaced parts on the Ro-Tap.
The parts are:
- Upper Eccentric Disc
- Upper Carrying Plate
- Lower Eccentric Disc
- Timing Belt Tensioning
- Hammer Block
Why Do I Need to Replace Parts?
Like its name, Ro-Tap, the machine literally rotates while a hammer taps on the sieve stack. This movement is what helps the particles being sieved find the openings efficiently. But, when this much movement is involved with metal bearings and parts, there is going to be some wear and tear over time.
Sieve shakers are very durable machines. We get calls from people that have purchased our machines over 100 years ago, and they are still using them today.
Just because they last a long time, doesn’t mean that they won’t need maintenance or don’t require upkeep.
We like to say that during the first year of using a brand new Ro-Tap, you shouldn’t need to change out any parts. Some oil along the way on parts that are rubbing may be required, but it should work smoothly.
After a prolonged period of use, you may begin to see some of the major parts starting to show some wear.
It is also dependent on what materials are being sieved. If you are running tests all day in your lab, you may find that your machine wears faster than someone who is only running 1-2 tests a week.
Most of those parts are easily replaced when following simple instructions. This allows you to minimize downtime as well as handle the issues in-house.
#14a Upper Eccentric Disc
- Unplug the machine and remove any sieves or loose items from it.
- Remove the Pedestal Cover (R-40011) from the side of the tower.
- Remove the Hammer (R-20029 and Hammer Block (R-20023) assembly by removing the ½-13 bolt from the bottom of the upper block and the inside of the tower.
- Remove the 3/8-16 bolt at the top of the Main Shaft (R-20027) - top of the tower near the inside edge.
- Remove the Upper Main Shaft Washer (R-10038), Sheet Guard (R-30019) and Rotating Guard (R-30010).
- Remove the Eccentric Disc (R-10034) from the Upper Carrying plate (R-30008- plastic or R-30008-1- Aluminum). Set aside Main Shaft Key-Eccentric (R-10042).
- Inspect the hole in the Upper Carrying Plate that the Eccentric Disc was in. If it is in good condition, skip to Step 8. If it is worn, the Upper Carrying Plate should be replaced, please see below.
#9 Upper Carrying Plate
Remove the two bolts holding it to the Tie Rods. Replace the worn Upper Carrying Plate with the new one and tighten the bolts back into place.
- Place the new Eccentric Disc into the hole in the Upper Carrying Plate and onto the Main Shaft.
- Insert the Main Shaft Key into the keyway in the Main Shaft and Eccentric Disc, align and insert.
- Reinstall the Rotating Guard, Sheet Guard and the Upper Main Shaft Washer.
- Tighten the Main Shaft with the 3/8-16bolt, reinstall and tighten. *Note: if the Main Shaft has dropped during the replacement, this will put it back into place
- Reinstall the Hammer, Hammer block assembly with ½-13 bolt into the bottom of the upper block on the inside of the tower
- Reinstall Pedestal cover.
#14b Lower Eccentric Disc Replacement
- Place the Ro-Tap on it’s side to gain access to the bottom of the machine.
- Loosen, but do not remove the 4- 3/8-16 bolts holding the Motor (P-1500-23) in place. Slide the motor to put some slack in the Timing Belt (R-10058).
- Remove the 3/8 -16 bolt at the bottom of the Main Shaft (R-20027).
- Remove the washer and then pull the Timing Belt Pulley (R-30015) and the Main Shaft Key- Lower (R-10039) off the Main Shaft (R-20027)
- Remove the Eccentric Disc (R-10034) from the Lower Carrying Plate (R-30009) and Main Shaft (R-20027).
- Slide the new Eccentric Disc onto the Main Shaft and into the hole in the Lower Carrying Plate.
- Install the Main Shaft Key-Lower into the Eccentric Disc and Main Shaft keyway.
- Slide the Timing Belt Pulley back onto the main shaft, making sure that the inner gear on the Timing Belt Pulley meshes with gear on the Cam Gear without damaging the Cam Gear.
- Reinstall the Main Shaft Key-Lower into the keyway on the Timing Belt Pulley and the Main Shaft.
- Put the washer and the 3/16-16 bolt back onto the bottom of the Main Shaft and tighten.
- Reinstall Timing Belt, push the motor back into position and tighten the 4- 3/6-16 bolts to fasten the motor.
#43 Timing Belt Tensioning
Timing belt installation should be a snug fit, neither too tight nor too loose. The positive Grip of the belt eliminates the need for high initial tension. Consequently, a belt, when installed with a snug fit assures longer life, less bearing wear and quieter operation.
Preloading is not necessary. When torque is unusually high, a loose belt may “jump teeth” on starting. In such case, the tension should be increased gradually, until the satisfactory operation is attained.
A good rule of thumb for installation tension is as shown, and the corresponding tensioning force in the RX-29 and RX-30 is 13.0 lb. per span.
*For the RX-29 and RX-30, the span length is about 9”, so the belt should be able to deflect about 1/8” when properly tensioned.
#3 Hammer Block
- Remove Pedestal Cover (R-40011)
- With a ½” socket or hand wrench, remove the Hex Head Screw (ZZ10068) and Lock Washer (ZZ10323) located on the top inside of the tower
- Remove the small set screw (ZA10148) located on the top of the hammer with an allen wrench
- Place the Hammer Block (R-20023) on a sturdy bench and with a drift or flat ended punch tap the Hammer Pin (R-10035) out of the block.
- Remove the hammer from the block
- Place the hammer onto the new block and tap the hammer pin back into place.
- Replace the small set screw and lock washer on the top inside of the tower.
- Replace Hex head screw and lock washer
- Replace pedestal cover
If the hammer isn’t tapping we have some steps you can take to possibly troubleshoot this issue.
Note: Prior to hammer adjustment; make sure plug is seated firmly in sieve cover.
Make sure sieve cover has top edge flush with upper carrying plate. A stack of sieves must be used to achieve this setting.
STEP 1: Remove the pedestal cover.
STEP 2: Jog machine until the hammer rises to the maximum height or use a ⅝” wrench on the hex head screw, located on top of the pedestal. Check height with square or scale
STEP 3: Set the height to 1-5/16 + 1/16” by loosening the screw on coupling and adjusting lift rod.
STEP 4: Tighten the screw on the coupling.
STEP 5: Replace the pedestal cover.
To Sum It Up
We hope this article helped you maintenance your Ro-Tap Sieve Shaker. When it comes to sieve shakers it is important to remember that they are all “noisy” to a certain degree. The important thing to listen for is those specific noises or indicators that you have have a part that is worn out or needs to be replaced.
If you are looking for more information on the Ro-Tap, here are some resources that may be valuable to you:- Why is my sieve shaker too noisy?
- Everything you need to know about the Ro-Tap Sieve Shaker
If you need to purchase parts for replacement, you can reach out to our customer service department to order them.