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Thread: Trouble Shooting a Brute Force Grizzly Feeder

  1. #1
    George Baker

    George Baker

    Vice President- Corporate Communications

    Assinck Ltd. [eDir]

    Assinck Ltd.

    Professional Experience 39 Years / 9 Month George Baker has 39 Years and 9 Month professional experience

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    Trouble Shooting a Brute Force Grizzly Feeder

    Had an interesting one the other day.

    CUSTOMER COMPLAINT: His new feeder on a portable plant was not FEEDING fast enough to keep his new HP cone choke fed. The loader was waiting for the feeder to empty and had to meter his bucket load vs quickly dumping and returning.

    OBSERVATION: Did field inspection, it was pouring rain, nasty DARK clouds and had a 988B Cat working around me. I asked the driver to keep an eye out for me, he smiled and said no prob.

    TROUBLESHOOTING STEPS: I watched the load and it was moving nicely from feed end of this brute force grizzly feeder. Noted that material (crushed rock and fines) slowed down and ganged up at the discharge end of feeder prior to dropping into the JAW opening. Hmmmm....fascinating but, why?

    RPM AND STROKE CHECK: RPM was 800 on a hydraulic drive connection to a CAT GEN SET on this portable crusher spread. RPM was not a prob.

    STROKE CHECK: This was the key to the solution. Stroke LENGTH measured out fine as 7/16" long - PERFECT. The feed end stroke READ about 55 degree Angle off zero degree vertical. The centre stroke check at the drive position reads the same. The discharge end STROKE check was NOT 55 DEGREE as it really should have been. It was like almost flat or horizontal. THIS makes a RED LIGHT GO ON......mayday.....PROBLEM Houston.
    This stroke should be balanced all around the unit and it obviously was not. This was the reason the MATERIAL slowed right down and almost stopped at the grizzly bars.

    RECOMMENDED FIX: This particular unit was 43" wide x 20' long with 5' of grizzly bars at the discharge end. The coil spring setup on this unit was across the underside (not outboard) about 5' back from the grizzly area overhang design. The only thing that would allow the stroke to be flat is the flattening out or compressing of the coil springs. This was in fact the case, new springs were installed - in fact a tad heavier rating and this corrected the problem and to the point where the operator was stopping the feeder now........due to overflowing the cone.

    LASTLY: The BACKUP spring on this unit was also discovered to be HARD TIGHT vs backed off 3/4" from the backup plate underneath the feeder. THIS in fact restrained the machine from going thru its natural free FLOATING action, made the motor work harder to run the unit and decreased the efficiency of the feeder due to RESTRICTING ITS FULL MOTION.

    Happy Crushing...........George Baker 519-242-6664 CANADA

  2. Dear Mr. George Baker,

    For the discharge capacity you have mentioned many things, but not the inclination of the grizzly feeder. The feeder discharge can be remarkably increased by increasing the inclination by 2 - 3 degrees, provided the deck is of sufficient length and the material repose line is within its limit.

    Regards,
    Ishwar G Mulani.
    Author of Book : Engineering Science and Application Design for Belt Conveyor.
    Email : parimul@pn2.vsnl.net.in
    Tel.: 0091 (0)20 5882916

  3. #3
    George Baker

    George Baker

    Vice President- Corporate Communications

    Assinck Ltd. [eDir]

    Assinck Ltd.

    Professional Experience 39 Years / 9 Month George Baker has 39 Years and 9 Month professional experience

    Discussions 883 George Baker acceded to 883 discussions, Articles 0 George Baker wrote 0 articles, Publications 0 George Baker Baker released 0 publications

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    Know-How Screening (373) George Baker used this tag 373 times, Manufacturer (110) George Baker used this tag 110 times, Conveying (28) George Baker used this tag 28 times

    Feeder Capacity

    Yes you are correct. I did not mention the angle of inclination of this brute force grizzly feeder. It is presently at ZERO degrees setting.

    It is on a PORTABLE feeder/jaw plant AND is at its maximum height for travel on the road and stay under 13' 6" requirement to go under bridges.

    ABSOLUTELY: You are correct. The allowable angle on a feeder like this is 10 degrees actually by the rules. Actual angle is dictated by Portability factors and yes, the angle of repose of the actual material being handled.

    Post Note: Most manufacturers install at ZERO degree and 45 deg timing out of their shops. I love to speak to the customer PRIOR to ordering AND review this concept.

    Go to 3 degree install angle. What does this do? It gives you a much greater range of flexibility with your operation - ESPECIALLY if you are wanting more TPH. At 3 degree angle and assuming FIXED spring supports vs trunion type, I can actually raise the feeder 3 degrees to 6 degrees or lower from 3 degrees to 0 degrees without having to change the spring setup.

    If I have a problem at 3 degree angle, it will be OVERFEEDING the jaw, I can just put a slower motor sheave on, which pays back dollars by increasing B10 bearing life and runs the machine under the design limits vs always PUSHING to the excess of the design limits.

    ALTERNATELY, Like most people and my theory is this is strictly old way thinking (TRADIITION) install at zero degrees. Now, if you have a problem with not enough TPH, what does Mr. Customer do? He gets a faster pulley somewhere in the quarry, slaps it on and GO likes crazy to increase TPH. The result is drastically less B10 bearing life, more bearing changes, and things like the sideplates cracking due to pushing the design theory by operating at excessive RPMS.

    Thanks for your imput, much appreciated. Come again.

    GEORGE BAKER, Moderator

  4. Anyone ever do a timing change on vibrating grizzlys? i have found in our situation slowing the feeder down with less angle gives more stroke. helping to break up and keep sticky material moving better,,, we run inverter drives so speed control is infinite and feeder is at 2 degrees incline .

  5. #5
    George Baker

    George Baker

    Vice President- Corporate Communications

    Assinck Ltd. [eDir]

    Assinck Ltd.

    Professional Experience 39 Years / 9 Month George Baker has 39 Years and 9 Month professional experience

    Discussions 883 George Baker acceded to 883 discussions, Articles 0 George Baker wrote 0 articles, Publications 0 George Baker Baker released 0 publications

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    Know-How Screening (373) George Baker used this tag 373 times, Manufacturer (110) George Baker used this tag 110 times, Conveying (28) George Baker used this tag 28 times

    Changing Timing Gear Angles

    Hello Kasey: 95% of brute force feeders come out of shop at 45 deg timing ANGLE from zero degree horizontal as a "standard" timing angle. Note: Some machines may not be able to be timed to every degree setting because of shaft size, offset, etc - the factory should be consulted in these cases. IE: if shafts are too big for example and timing is dropped to low - you may hit the shafts upon rotation and lock the shafts up.

    The last thing we want to do, as it is the MOST COMPLEX --- is to open up the drive and change the gear angle timing. We typically try the easy things first, raisiing or lowering the angle of the FEEDER BODY or SPEEDING UP OR SLOWING down the RPM of the feeder. If these do not work, we change the timing.

    Lets look at what we got here:

    1) Assume 45 timing angle: this is a mid range angle which allows material to be thrown up in air, move towards discharge end of the feeder and "de-fine" at the grizzlies sections and put overs into CRUSHER CAVITY.

    2) Lets assume we have material GANGING UP and moving in a masse down the feeder in a "HUMPING EFFECT". If I want to move from feed end to discharge end faster, I could adjust timing angle DOWN to say 50 degrees off 90 DEGREES VERTICAL and the material travel rate would increase and tonnage rate would increase also.

    3) CONVERSELY, and just for example purposes: If I changed the TIMING ANGLE TO 90 degrees off zero degrees Horizontal. the material would be thrown UP in the air STRAIGHT UP and the foot travel would be ZIP ALL or zero and the material would just go straight up and down and not move from feed end to discharge end. This is why we are allowed to change timing angle to help foot travel rate and get A NICE ANGLE OF REPOSE of material filtering itself onto the grizzly bars vs coming on to the grizzly bars in a SURGE LOAD CONDITION and being inefficient when it gets there.

    Angle of the feeder body: I always love to install and suggest to install at 2-3 degrees vs zero. At zero degree - if I have a problem with not enough TPH - i must recommend speeding up feeder which gives me more TPH quicker but, also DECREASES B10 calculated bearing life and runs feeder at high side of the ENGINEERS design limits and could lead to a side plate failure.

    CONVERSELY> if I INSTALL at 3 degrees for example, my prob will be OVERFEEDING. if this is the case I must slow feeder down which increases B10 bearing life and makes machine body last longer running at lower G FACTOR.....A very desirable thing....PLUS PLUS PLUS. (PS - GRAVITY IS FREE)

    TIMING GEAR CHANGE PROCEDURE available upon request, quite deailed deal.

    Thanks for participating..........George Baker, MODERATOR

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