Intro to Millwright Practice Exam

Which of the following is a puller with two plates clamped together by all thread and placed behind the object being moved?

1. Clamshell

2. Hydraulic Puller

3. Wire Rope Come-Along

4. Chain Fall

The correct answer is: Clamshell

The correct choice identifies a puller known as a clamshell, a device specifically designed for pulling or lifting heavy objects. The clamshell mechanism typically consists of two plates that are clamped tightly together using all-thread bolts, which allows the user to exert even pressure and secure the object more effectively. This design enables the device to grip onto objects from behind, facilitating the movement of the object it is attached to. In contrast, the hydraulic puller relies on hydraulic pressure to achieve the same purpose but does not utilize clamped plates and all-thread bolts. A wire rope come-along uses wire rope and mechanical advantage to pull objects and is not constructed with the dual plates concept. The chain fall is generally employed for lifting loads vertically using chains and does not involve a clamping mechanism like a clamshell. Hence, the design and function of the clamshell specifically match the description provided in the question.