The forklift market is steadily increasing with demanding of electric forklift due to problems such as manufacturing unit cost, environmental impact, and maintenance. Especially, demand for small electric forklift trucks is expected to continue to increase as the logistics market is expanding and demand for operation by minimizing the turning radius and optimizing the warehouse is increasing. Accordingly, product reliability verification is required along with the development of a compact-type three-wheel drive train system that incorporates EPS modules.
The purpose of this study is to accomplish the structural analysis of HOUSING, and to verify the durability of the product by designing the accelerated life test method on the assumption that the life time of the product is dependent on the Weibull distribution using steering axle of 2-ton electric forklift.
First, the safety factor was secured by assessing the flexural rigidity and contact stress of six gears made of SCM420H, and the structural analysis of housing made of FCD45 was performed to confirm that the housing has sufficient strength for the load. The accelerated life test code is designed based on data from vehicle test and RS B 0073 (drive axle for medium-sized forklift) and the reliability evaluation standard established by KIMM(Korea Institute of Machinery&Materials). In order to implement the accelerated life test by testing code, a testing machine was constructed to implement the load on the steering axle and testing durability of not only housing but also the gear by adding to load to the steering axle, unlike the existing test method that was only used for the driving test. Using the accelerated life test code developed, the test was performed for a total of 360 hours repeating the test for 11 hours in forward and 11 hours in reverse.
The reliability of the Steering Axle was verified by disassembled specimen after accelerated life test was completed and conducting a gear precision test and a housing penetration inspection.