Can you post the drawings?

Rgds, ■

If the sealing arrangement leaks then it's not up to the job.

You need a better design. Consider multi seals with a grease purge between the seals. ■

I once had a similar problem, and after performing all normal troubleshooting checks ... and trying different types of oil seals and sealing arrangements (all with no joy), the problem proved to be due to excessive shaft deflection due to eccentric weights. Solution was to increase the shaft dia in the center section and the problem was solved. Perhaps this may be worth checking out in your case. ■

Originally Posted by keshav

Dear all,

What are the major reasons for oil leakage in a vibrating screen?

The Vibrating screens we manufacture have a nagging problem of oil leakage. We have provided a splash lubrication system for our bearings. To prevent oil leakage we have provided a rubber lip type oil seal on the bearing cover.

However, oil still leaks from the clearance b/w the bearing cover and the shaft.

Please Help!

Keshav

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Greetings and salutations Keshav,

As Designer and John Mckensie, have described so well it can be these two culprits.

is it possible the oil bath is overfull- remember to look at the screener with an eye to the actual oil level as the system is connected to the screener- remember that splash lubrication means intermittent splash with no oil bath.

Is a compression gasket used in this location in addition to the shaft seals?

Do the oil seal lips face the oil flow(meaning towards the inside of the gearbox) rather than away from it-Thats a big one as they must face the oil flow or splash to seal properly or they are useless.

If the motor speed is high the seals may be wearing out prematurely;

using Derrick screens for an example the screen oiling system pumped fresh oil through through the system and the oil was collected in the waste oil bottles on the opposite side.

If the seals are not strong enough or do not have additional seal surfaces or do not have a coil spring backing to maintain the seal lip profile they will loose oil, if you have a pressure build up the oil will have to go some where and the seals will be the culprit if no gearbox vent is used.

Take Designers and John Mckensies advice and recheck everything and if possible

obtain a pressure reading inside the oil bath case(if possible) to see what pressures are building up if any as this too could be a problem if the case is not vented like the Derricks screens example with the waste oil bottle.

Rotating the screen motor shaft at operating speeds by itself(for a time to check for deflection and metal fatigue) with no screener attachment is warranted to check for deflection with a dial indicator or laser as John Mckensie has mentioned is a must to rule that out.

Do you machine your own motor shafts for the screens or are they provided for you from an outside supplier with the motor assembly such as as how the derricks are designed which are this way if my recollection is correct and looking left to right-

Waste oil drain-bearing-exciter weights-motor shaft-motor-shaft-exciter weights-bearing-fresh oil delivery line.

Perhaps you simply need a simple case vent with an extension tube to vent it such as the waste oil bottle is used for the Derrick screens example which in practice also flushes old oil, collects it and pumps new oil in to the screen motor bearings.

Not having a picture or drawings limits us as our friend sganesh has so kindly expressed in his question.

lzaharis ■

Most of the vibrating screens I have commissioned over the years have been splash oil across the shaft tube assembly. Typically we fill oil to oil level indicator on side of machine and we should be good to go ...........so to speak. lots of the machines are also oil in the END COVERS ONLY and not splashing across the tube.

- most of the units in fact do have a outer EP GREASE seal.......AS a secondary dust seal to protect the JM.....(johns mansville double rubber lip seal)

- it is very common for people to experience annoying oil leaks for a number of reasons---the key is to identify where MR OIL LEAK is originating from.....ya know from the 12 oclock or top of the brg hsg position or 6 oclock position bottom of brg hsg.

- if top.....and oil is running down from there, there would typically be the OIL BREATHER position (12 oclock)

- Why would it leak from there.....Hmmmmmmmm...if you overFILL the oil in the shaft tube.....when the shaft TURNS...it is FORCED to DISPLACE large qty of fluid in front of it as it turns.....oil heats up....expands....and BLOWS out the breather position to escape its tight quarters.

- So ...the key to stop that type of leak is to fill to the proper level on thee oil sight glass, mounted on the sideplate. The position of the fill line will be 1/2 way up the bearing ROLLER position normally, so we splash thru the oil laying down in the bottom of the tube assembly., but do not create HEAT due to overfill situation.

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- Oil leaking at the 6 oclock position. Sometimes when oil leaks here it idicates the JM DOUBLE LIP SEAL which should be tight of the polished shaft surface becomes OPENED......this can be caused by rough handling upon seal install, or worn shaft at that position or....rubbers are a tad LOOSE. We would go out and replace with new seals as first thing here. But, if we got there and no new seal in the middle of NO WHERE tobe had. We would do a trick.....pull stainless steel coil from back side of rubber seal, pull male end out of the female end, snip a 1/64 or 1/32 off reinstall the ends, which makes rubber hold down to shaft a bit tighter and VWA....LA.........no more leak........and it works.

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OIL IN END COVER DESIGN: Another common cause of oil leaks.......if people DO NOT KEEP THE OIL BREATHER holes CLEANED.....so tube assembly can BREATHE.........we end up causing heat buildup......inside the TUBE COVER ENDS.....the oil heats up excessively...expands...and actually PUSHES the 2 rubber seals open to allow oil to leak INTO the tube. SO keep the breathers clean and open or use a MUSHROOM HEAD BREATHER.....vs 3 little pin prick holes.

- sOMETIMES we must be careful not use a synthetic oil type that allows the oil to deteriorate the rubber in the lip seal.......NOT REAL COMMON ...but, does happen at times.

A bit of a leaky situation. ■

The mechanism has to be redesigned - you need a labirynth and rubber seal.

Regards

Ziggy ■

Keshav

I would need to have a look at the dwgs of your mechanism.

"Re checked the water level of the shaft at both sides - drive and driven (In fact the driven side was at a slightly higher level)" - what do you mean driven side was higher?

Regards

Ziggy Gregory

ziggy.gregory@vibfem.com.au ■

Originally Posted by keshav

First of all my Greetings and thanks to Mr. Izaharis and Mr.George Baker for their help.

I have implemented some of your suggestions:-

a. Proper Air vent has been provided

b. Compression gasket has been used at the bearing covers

c. Extra care been taken in the installation of oil seals

d. Excess oil has been removed from the chambers

Oil leakage is much under control.

However, something is still baffling me - and i am completely out of my wits - Oil leaks out only from the driven side of the machine. To investigate, I have done the following:-

1. Re checked the water level of the shaft at both sides - drive and driven (In fact the driven side was at a slightly higher level)

2. Re checked if there was any difference in counter weights on either sides

3. Replaced the oil seal

4. Reduced the clearance b/w the shaft and the bearing cover

No avail - after one hour of operation - the oil dripping re starts. This phenomenon is being observed in all our machines

If seems as though something is pushing the oil inside towards the driven side of the vibrator

Please help

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The frames for the motors:

Are they welded to the sides of the screen side frames or bolted to the side frames?

If they are bolted to the side frames are there flat washers under one side and not both sides of the motor or mounting frame where it is attached to that side frame of the screen and not on the other side?

My last thought is oil viscosity BUUUUUUUT it sounds like an assembling problem prior to testing as something involving the motor is not level........

Check the motor housing for level then check the cross frame that the motor exciter is anchored to for level at the front of the mounting and rear of the cross frame

If that steel is warped or weak-oh boy!!!!

Check the side to side distance from the outer frame corner to corner and diagonally; then

check from side to side for level it has to be there ■

Well, going out of your wits.....we sure don't want that. We aim to try and please here in this forum. I see my good buddy Leon (izaharis) has been giving lots of advice also. A good man Leon.

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So, let keep trying here then:

- Is the whole vibrating body, level all around in each corner, do a transom check to confirm. Uneven, equals oil levels uneven.

- Pls advise the type of oil. Exact spec off the supplier spec sheet please. Is is EP RATED OIL? 220, 320, or?

- Pls describe your oil seal stackup on both sides. If using an aluminum or white metal seals.....it has happened to me....before, that the seal is out of round or defective or oversize by a bit.....and the machine will always always leak. I had a customer with this problem for 1.5 years replacing seals constantly and finally had the seal miked UP and found it to be wrong from the supplier and we had new seal made properly and the LEAK was corrected and stopped. BUT IT TOOK A WHILE TO FIND AND FIX THIS DEAL.

.........

DO you have an expansion side setup of the seal arrangement on one of the sides....preferably the side opposite the drive side?

IF NOT this can cause problems.

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Normally, bearing problems occur on the DRIVEN SIDE. If belts are TOO TIGHT, you can put pressure on the driven side bearings and cause leakage and or bearing failure.

- Are the DRIVE BELTS PERFECTLY ALIGNED, straight? vs cocked.....this can cause oil leakage.

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What is the bearing specification? Is it designed for vibrating screen duty with proper C4 F3 clearances....for a vibrating screen duty?

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CAN you confirm the OPERATING TEMP OF THE OIL? with a heat gauge??? If you confirm the TEMP.....and you are running HOT......oil expands when heated and as mentioned before.......if breathers are plugged or orifices are not big enough to disipate the heat......oil can and will BE FORCED across the drive side to the side opposite thru the tube assembly.......under PRESSURE.

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