Jacking is the lifting or lowering of heavy loads with the help of climbing jacks. A climbing jack is a specially constructed hydraulic jack with a plunger that is used upside down. The plunger can move in and out at the bottom of the climbing jack. The jack casing pushes the load up or lowers the load downward.
By using a climbing jack in combination with timbers, the load can be lifted following these steps: Step 1: This is the starting point before jacking takes place. The climbing jack is placed underneath the load on top of several timbers. Seven (7) timbers are placed in such a way that the 3 in the middle are placed underneath the plunger of the jack.
Step 2: By pushing out the plunger using hydraulic pressure, the load rests on the 3 middle timbers. At the outer side of the jack we have now created free space.
Step 3: When the space created in step 2 is big enough, this space can be filled with 4 timbers and two distance strips. The 4 timbers with strips are placed transverse on the others to increase the stability of the timber stack.
Step 4: After the new timbers and distance strips are placed, the plunger can be retracted. The load will rest on the timbers and the distance strips. The space that is created by retracting the plunger will be filled with 3 timbers. By using distance strips in step 3, enough space is created to easily place these 3 timbers under the retracted plunger..
After completing Step 4, the load has been raised by one timber height (the plunger could be pushed out and retracted a small amount to remove the distance strips). By repeating Steps 2-4, the load can be lifted multiple timber heights.
The lowering of a load is also possible with climbing jacks. This is done by following the above steps in reverse order.
