This simple lowering mechanism consists of a steel cylinder or box filled with dry sand, supporting a wooden or metal plunger. The heavy load rests on the plunger, and workers slowly drain the sand through a small plug hole at the base to lower the load with extreme precision. They are heavily utilized in bridge building and heavy timber construction to remove temporary shoring or position massive structural elements without complex hydraulics.
Heard on the job
We'll set the main girders on sand jacks so we can drop them into their final pockets a fraction of an inch at a time.
Insider tip
The sand must remain bone dry to work properly. If moisture gets into the cylinder, the sand will clump and refuse to flow out of the release port.
Also heard as
- sand box