A manufacturer of straddle carriers, off-road vehicles for handling shipping containers in port terminals and intermodal yards, recently turned to GGB for a solution that would improve the performance of its equipment.
Straddle carriers can lift up to 60 tons and stack cargo containers four high. Committed to minimal maintenance, the company sought to replace a greased bronze bushing in a key chassis component, specifications for which included long service life, maintenance-free performance and quiet operation.
MAINTENANCE-FREE, CUSTOM BEARING ASSEMBLY
GGB developed a custom bearing and axial thrust washer assembly that eliminated the noise and need for lubrication posed by the bronze bearing. The specially designed GGB GAR-FIL® bearing consists of a proprietary filled PTFE tape liner on a backing of continuous wound fiberglass encapsulated in a high-temperature epoxy resin.
This composition and structure provide high load capacity, good friction and wear properties, good impact resistance and high elasticity modulus. The bearings do not swell from moisture absorption, and their inert nature makes them suitable for corrosive environments such as seawater.
DUAL-POLYMER THRUST WASHER
The axial thrust washer is made of GGB EP®22 and EP®30 engineered plastics materials in a dual-component assembly. EP®22 is an extremely robust PBT-based, PTFE-modified dry bearing material with low moisture absorption, and EP®30 is a PA 6.6-based polymer modified with AF and PTFE additives.
The two materials combined to eliminate noise and reduce stick-slip behavior. In addition, they were matched to the shaft material for less wear and long service life. Significantly, the GGB solution was dimensionally the same as the bronze bearings it replaces, eliminating the need for costly modifications and facilitating the retrofitting process.