No Degradation of Scissor Lift after Five Years

Leading dock-levelling and materials-handling specialist REV Designs & Installations has steadily grown into one of South Africa’s most innovative engineering firms in the lifting-equipment sector. Based in Springs, the company designs and manufactures a wide range of loading, docking and lifting equipment including some of the largest scissor lifts ever produced in the country.

A key factor in the success of the business is the careful design and specification of materials and components which amplifies its equipment’s’ performance and results in trouble-free operation for its customers.

Key pivot points

A good example is the design and construction of three massive scissor lifts destined for the timber industry several years ago. Each capable of handling up to 40 tonnes per lift, the lifts were engineered for harsh, high dust sawmilling environments where the equipment is pushed hard and uptime is critical.

It was during this period that founder and chief designer Ricardo Viljoen made a key engineering decision to move away from greased steel bearings and fully adopt igus high-performance polymer bearings across the key pivot points of the new lifts.

Striking service history

According to Ricardo, the switch has exceeded expectations. The original scissor lifts have now been in operation for around five years and the service history is striking. The machines were designed to be serviced quarterly with an annual inspection recommended.

In practice REV has only been called back twice in five years, once for a light annual service and again for a general inspection. Since that time not a single bush or bearing has failed.

Trouble-free

This small move away from conventional design has saved the customer many hours and costs that would otherwise have been associated with servicing and maintaining greased steel bearings as well as the unavoidable failure of these bearings that would have previously allowed for several failures per lift per year.

Says Ricardo, “The igus polymer bearings have operated without lubrication nor adjustment and without any sign of wear severe enough to warrant replacement. The scissor lifts themselves have also run trouble-free reinforcing the success of the bearing choice and overall design. Our customer’s own maintenance teams have confirmed that there has never been a problem with the bushes, never a problem with the scissor lift or anything else associated with the scissor lifts.

Direct impact

“This kind of long-term reliability in a demanding environment has had a direct impact on our design philosophy. Today, all new scissor lifts as well as numerous other loading and lifting solutions produced by the company are standardised on igus polymer plain bearings and bushings”

Ricardo explains that bearings need to be exceptionally strong to handle the massive forces generated during heavy lifting. At the same time they have to resist the ingress of debris that quickly seizes or damages metal-on-metal bearings.

Notoriously harsh

The sawmilling sector is a good case in point. It is notoriously harsh on mechanical systems with fine sawdust, moisture and abrasive debris destroying traditional bearings which requires frequent greasing. Cleaning joints to remove grease and buildup also releases contaminants into the environment and if left ungreased, the heavy loads and repetitive motion quickly accelerate wear.

Working closely with Juan-Eric Davidtz, igus’s polymer bearing specialist, REV is able to identify the correct iglide materials for each pivot point on scissor lift pivot, caster or other moving application. For example, the timber scissor lift incorporates 33 bushings, each one operating under slightly different conditions including load, movement or weight. Matching specific polymer formulations is critical to each requirement and ensures optimal performance throughout the system.