Bearings
Dont you just love it when a client tries to tell you that somebody elses machines are better than yours.
You can certainly tell that they have not examined the issue to the extent necessary, and that they suffer from severe tunnel vision, driven by production demands figuring that if they can speed up screening that will speed up production.
I will give you a great example- The folks I used to work for bought an 8 by 16 or 24 simplicity- I think it was this size anyway.
So the big day comes and the new screening plant is finished with seven hunderd tons of steel for the entire installation the screen in question feeds a "Spokane" crusher.- now here comes the good part-are you sitting down?
The screen in question started operating and sped up to full RPM,
In the process the vibration from the screen was so severe and violent that the entire frame of the screening plant was vibrating and shaking to the point that you could not walk safely let alone
service the equipment
Guess what Simplicity told them to do?????????????????????????????
Add 10 or more tons of steel to the mounting frame under the screen to stabilise it !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!!!!!!!!!!!!!!!!
Its pretty bad when you tell them to install air bags to isolate the vibration and they do not listen.
So much for being knowledgeable about a subject.
my two cents ■
Do bigger bearings mean Heavy Duty?
This is an interesting topic, my customers over the years bring up.
1. When comparing a vibrating screen quote to a competitor, I have had many instances where the enduser will joyfully point out the inadequacy of my quoted unit vs a competitor.
2. Your bearings are not as big as ABC company. You are NOT as HEAVY DUTY...... and we want heavy duty.
3. An actual example: We were quoting an 8x24 3 deck inclined screen with dual 160mm bearings for drive assembly...big body static weight. Competitor was quoting same size screener with dual drive also, but, 200mm bearings.
4. Client looks at quote, compares and states: Competitor unit is better unit.....much bigger bearings, means more heavy duty, better for my job.
5. Now ......... I must do my job. I state, NO, in this case BIGGER IS NOT BETTER. Customer states.......I do not believe you, WHY?
6. On the outset, quick look reveals customer opinion that 200 mm bearing is bigger, is in fact CORRECT. Is it better, NOT NECESSARILY......and in fact in this case........NOT.
7. The reasoning is this: the 200mm bearings are in fact, limited to the top end RPM they can run by bearing manufacturer's own rules. Typically will run in oil, seldom in grease on this big, as the RPM is limited even more.
8. The 160mm bearings being smaller OD can in fact, run faster and still maintain a miniumum 10,000 operating hour L-10 bearing life range assuming well taken care of in operation.
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The availability of operating speed FLEXIBILITY is very critical here to accomplish EFFICIENT SCREENING desired. Remember it is a 3 deck screen, variable openings, not just one separation.
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A BIG Machines means BIG TPH so we gotta move this rig with some decent operating RPM.
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If we move the top end speed on 200mm BEARINGS faster to screen more aggressively........we FRY the bearings in a dramatically shortened bearing life cycle.
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By going 160mm bearings and TWIN SHAFT.....2 bearings on each shaft.......times 2 shafts or 4 bearings total..... we in fact, gain the oopportunity to run faster and still maintain acceptable minimum L10 bearing life standards. Hence, maintenance costs are reduced, downtime reduced, uptime increased, TPH increased, operating costs decreased per TON PER HOUR. all good stuff.
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The 160mm design twin shaft also allows you FLEXIBILITY if, in the future you want to change ........say.........wirecloth decks to heavier RUBBER or URETHANE or PERF plate style which all are heavier than wirecloth. All would cause decreased L-10 BL.
The twin design allows you to add these changes and still maintain good bearing life.......because we have the static loads being driven more throughout the whole centre line of the screen box and the additional shaft and bearings gives me excessive or additional L-10 HRS vs one single shaft design.
Wishing all of our FORUM contributors and friends a happy, successful, FANTASTIC........2005......remember keep shaking out there.
Til next time.........George Baker ■