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Articles from CONVEYORS/CONVEYING EQUIPMENT (338 Articles)

Block unit overhaul beats bearing, shaft failures

A Hanson operation in the central west of New South Wales has turned to solid block housed units to address numerous bearing and shaft failures in its conveyor tail pulleys.

A maintenance program to replace all conveyor bearings with Timken SRB solid block housed units (previously known in the industry as Blue Brute housed bearings) has meant an end to bearing and shaft failures in the tail pulleys at the Hanson aggregate quarry at Molong in New South Wales’ central west region.

In continuous operation for almost 30 years, Molong Quarry has been an integral part of Hanson Australia since 2005.

One of the leading sites in the group, the quarry produces aggregate for construction and building projects throughout the central west region.

A series of bearing and shaft failures, predominantly in the conveyor tail pulleys, initiated a search for a reliable replacement in the tough working environment.

“By its very nature, a quarry is tough on components such as bearings,” said Molong Quarry’s manager Chris Cooke. “They are generally covered in dust all the time. And each time a bearing or shaft failed meant a couple of days’ lost productivity while the damaged component was removed and the replacement fitted.”

Cooke said the removal and replacement process would affect the site’s run of materials and also occasionally delay deliveries.

Designed to operate in the toughest of environments, the SRB solid block housed units (SBHU) are considered ideal for heavy-duty operating environments. They offer continual extreme load and speed capacity due to the size and number of the two rows of rollers. They are designed to allow for limited shaft and housing misalignment (up to 1.5 degrees from centre) and still work at full capacity. The bearings are distributed nationally through the BSC branch network.

An SRB SBHU installation.
An SRB SBHU installation.

“Around the time failures started we were invited to a workshop at the local BSC branch, where they were demonstrating the SRB SBHU product,” Cooke said.

“After having a good look at what they [the SRB SBHUs] had to offer, we didn’t need much convincing. The benefits were easy to see and gave us the solution we needed.”

The Molong Quarry uses the two-bolt pillow block unit, one of seven housing styles available. Four locking styles and seven seal types combine to offer a range of housed bearings to suit virtually any industrial work site and environment. The range will suit shaft sizes from 35mm to 180mm.

To improve maintenance access, Cooke installed greasing lines to the bearings.

“Some of the bearings are hard to get to, so we have installed grease lines to make them accessible from ground level,” he said. “The bearings have a purge feature so we can’t overfill them and they maintain their integrity and reliability.”

He said the bearings had met all expectations.

“They’re good. They keep working and we are not losing any time due to bearing problems on the conveyors. That’s the type of performance we want. And they last. We pulled one down recently as part of a maintenance program and, aside from a few scratches, it looked just as good as the day it was installed.”

Adaptable to harsh condition

The Timken SRB SBHUs are made from cast steel, giving equal load capacity in any radial direction and allowing simple horizontal mounting, with the inclusion of multiple levels of sealing to protect the bearing in operation.

An SRB solid block housed bearing unit.
An SRB solid block housed bearing unit.

Harsh operating environments often lead to housed unit bearing damage. However, the SRB SBHUs multiply protection with primary and secondary seal options, as well as steel covers in sizes to fit all Timken solid block housed units. Depending on the sealing configuration, up to eight layers of protection can be achieved to protect the bearing, maximising operational life.

Moreover, as most conveyor applications have some amount of structural misalignment, sealing efficiency can be compromised, reducing the life expectancy of most housed units. The SRB SBHUs, however, run efficiently on misaligned shafts up to ±1.5 degrees as a result of the unique design of the spherical roller bearing extended inner ring, where the primary seals run.

The SRB SBHUs are supplied pre-assembled, so there isn’t any set-up required, which reduces the risk of contamination and precludes feeler gauges during installation, as the SRB’s radial internal clearance is factory set. Moreover each housed unit can be simply adjusted during installation to make it a fixed or floating bearing unit, eliminating the accidental FX/FX issue from oversupply on components.

A range of shaft sizes, from 35mm (1.3”) to 380mm (15”) and mounting options are available.

The housing configuration can also be customised. The SRB SBHU offers interchangeable solutions for common SN, SAF and SD pillow blocks, flange and take-up designs that other manufacturers simply cannot offer.

Source: Inenco Group

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Saturday, 24 August, 2019 12:36pm
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