Shredder motor powers through blockages

Menzel Elektromotoren recently replaced a slip ring motor which had failed due to overload. The motor came from a shredder, designed for mixed scrap metal, which is able to process entire car bodies. The application had resulted in exceptionally strong vibrations being transmitted to the motor which disrupted the contact between the carbon brushes and slip rings, causing sparks, brush fire and severe damage to the slip rings.

Menzel had a suitable unit to hand and quickly equipped it for the application. The slip ring motor is able to deliver the full starting torque from standstill. In the event of blockages or when starting up, the shredder does not need to be emptied first. In many cases, the motor starts the loaded shredder and powers through blockages.

Menzel equipped the motor with abrasion-resistant brushes, fitted springs with high contact pressure in the brush holders and installed more brushes to ensure a sufficiently large contact area for current transfer even if a brush momentarily lifts off. This was complemented by a range of measures for vibration damping and absorption as well as motor monitoring. A spherical roller bearing on the drive side absorbs impacts, compensates for slight shaft misalignment and, with good maintenance, achieves a long service life in shredding applications.

Menzel also helped define new best-practice guidelines for the shredder. In future, car bodies will be cut in half before being thrown into the shredder, especially electric vehicle bodies, whose underbodies are reinforced around the drive battery which makes them extremely hard to shred. An operational vibration analysis was also conducted, and temperature and vibration sensors were installed to continuously monitor the bearings and help establish an effective maintenance plan.

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This article appeared in Renew magazine. To read more or request your personal digital or print edition of Renew, click here.