Maintenance contracts generally contribute around half of the revenues of the big lift companies, providing steady income even when new orders head for the basement.
维修合同通常给大型电梯公司贡献了半数的收入，即使是在没什么新订单的时候，它也能提供稳定的收入。
2
The lift car in the elevator system has the advantages of steady operation and good acceleration effect.