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SAFETY BULLETIN 

Bulletin number: SB104

Category: Safety

Date issued: April 29, 2003

Machine models: TEI Prefeeders manufactured prior to 1994

Subject: Unexpected retracting of the extendo.

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To our valued customer:

This service bulletin is part of an ongoing effort to provide quality service and support for all Alliance Machine Systems International, LLC products. If you need assistance or more information, please call Gary Kneale, Field Service Manager, at 509-535-0356 and select Option two.

Description of Problem

The prefeeder extendo conveyor is used to shingle blocks of corrugated into the finishing machine hopper.  The extendo is comprised of two, telescoping sections.  The section with the tamping system, located closest to the die cutter, is called extendo section 2.  Extendo section 2 is extended and retracted with a power adjust mechanism.

There is a possibility that the power adjust mechanism may fail allowing the extendo section 2 to unexpectedly retract to the full-in position.  There is a possibility that a person may be struck by the tamper arm or the end of extendo operator station if a failure occurs.

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There are three designs that have been identified for review.

  1. TEI extendos manufactured prior to 1994
  2. Prefeeders that originally had a manual extension hand crank or a cable cylinder adjustment system may have been retrofitted with a kit that contained an acme rod nut mount with a three bolt pattern.  Verify the style of bracket on your machine and if it is the three bolt design, please do the following:

    1. Remove the three 3/8” UNC bolts and tap and replace with three 1/2” UNC grade 5 or higher bolts.  Torque  the bolts to 90% of the rated proof strength.

    2. Verify a quality weld exists and correct if necessary.  The weld must be continuous around the welded acme nut mount.  The weld should not have any discontinuities and the radius of the weld should be smooth.

    Figure 1. Three bolt mounting bracket.

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  3. TEI extendos with manual, hand-crank adjustment
  4. Early Prefeeders used a hand-crank to adjust the length of the extendo.  A holding device was initially provided with the machine.  If the holding device is not used or is used improperly, unexpected motion may occur.  If the machine matches this configuration, please do the following: 

    1. It is recommended to replace the manual, hand crank adjustment system with a powered adjustment system.  A retrofit kit is available to add an acme rod system driven by a hydraulic motor.

    2. If you choose to continue to use the manual, hand-crank adjustment system, please train all personnel using the equipment in the proper use of the holding device.  This includes using the holding device at all times when the extendo is not being adjusted.  The gear teeth must be fully-engaged.  Visually inspect the holding device each time it is used to ensure proper use.

    Holding Device Fully Engaged

    Holding Device Disengaged and Clamp Tightened

    Figure 2. Hand Crank

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  5. TEI extendos with a cable cylinder adjustment system
  6. Early Prefeeders used a cable cylinder to adjust the length of the extendo  If the machine matches this configuration, please do the following: 

    1. It is recommended to replace the cable cylinder adjustment system with an alternative powered adjustment system.  A retrofit kit is available to add an acme rod system driven by a hydraulic motor.
    2. If you choose to continue to use the cable cylinder adjustment system please inspect the cable and fasteners monthly and tighten as necessary.  Replace the cable cylinder if defects are identified.

     

    Figure 3.  Cable cylinder system.

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