Yun,<br>
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Contact Handling Specialty, Grimsby, Ontario, Canada. They build scissors lifts and will perform special analysis if needed. Most manufacturers of these lifts need to make many many copies of a single design to break even so they are not likely to do specific design work - once they get it right they "stack 'em deep and sell 'em cheap!" <br>
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The basic sizing requirements of these lifts are not too hard to analyze - it just takes time. Friction can significantly complicate analysis, especially as multiple stages are used.