Bulletin: SVB-116

Date Issued: January 24, 2006

Category: Design Improvements

Subject: Inverter Structural Design Correction

Machine Models: High-Speed Top Feeders

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Problem

Recommended Action

Modification Procedure

Problem:

One of our customers reported experiencing a significant structural failure of the welded joint assembly on the operator side of the machine where the inverter pivot shaft assembly mates to the inverter frame. See photos below. The sagging inverter assembly on the operator side also caused weld cracking to occur on the drive side of the machine where the stub axle is attached to the inverter frame.  

This damage rendered the inverter assembly of the HSTF inoperative until a temporary weld repair was performed. This HSTF had been in service approximately 3 months prior to this event.

In response to this report, Alliance has redesigned the structural mounting of the inverter shaft assembly to the inverter frame on both the drive and operator sides. This change is now effective for all new production HSTFs.

For in-service HSTFs Alliance has developed a preventative modification to this welded joint. Four gussets are added to the joint on the operator side of the machine. Rework is also required on the drive side of the machine. The retrofit modification provides improved design strength and is structurally equivalent to the revised production configuration.

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Recommended action:

Alliance strongly recommends that maintenance personnel immediately visually inspect the inverter assembly for the presence of any cracks or damage in the areas shown below on the ends of the inverter assembly. This photograph shows the operator side of the inverter in the pre-modified configuration. Inspect this area on both the drive and operator sides of the inverter frame.

• If any cracks are found, do not operate the HSTF and contact Alliance immediately for further guidance prior to attempting any repairs. Depending on their size, cracks in the welds themselves can possibly be ground out and rewelded as a temporary repair. However, if cracks are found in the base material a technical evaluation by Alliance Engineering is required prior to proceeding further with any repairs.

• If no cracks are found, Alliance strongly recommends that you perform the preventative modification described below on each affected machine within 30 days after receipt of this service bulletin. The parts kit required to accomplish this modification will be provided under warranty at no charge to operators of the affected machines.

This modification must be performed by a certified welder. The modification procedure is anticipated to require up to 8 hours of elapsed downtime to complete, and Alliance will reimburse for labor charges incurred for the welding.

• If an in-house certified welder is available submit an invoice to Alliance Field Service for the welding labor charges after the repair is completed.

• If an outside certified welder must be contracted, please obtain an estimate for welding labor charges and send to Alliance Field Service for a review prior to proceeding.

The parts kit to accomplish this modification consists of four steel gussets and 6 longer bolts with washers. The parts kit and repair drawings will be shipped by the end of January.>

If you need additional assistance to perform this modification, please call Mr. Gary Kneale of Alliance Field Service at: (509) 842-5134.

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Modification Procedure:

1. De-energize and lock out the machine per the Operators Manual.

2. Gain access to the repair areas in the ends of the inverter frame shown in dwg # 1034953. Block up the inverter frame such that the weight of the inverter is taken off these joints and the joints are in an unstressed condition.

3. Add new welds to the drive side of the inverter frame as shown in dwg 1034953 sht 1.

4. Replace 6 bolts on the drive side inverter frame with the longer bolts per dwg 1034953 sht 3. Alliance recommends that you replace the bolts one at a time and apply the final torque when all new bolts are installed.

5. Add 4 welded gussets to the operator side of the inverter frame per dwg 1034953 sht 2.

6. Remove inverter blocking and restore the machine to the operating configuration.

7. Remove lockouts and resume inverter operation. Check for proper inverter rotation and operation.

8. Please advise Alliance when the preventative modification is completed. Please contact Mr. Gary Kneale at gkneale@alliancellc.net with your confirmation message.

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