Use & Operation of Common Pressure Power Pack

A common low cost method of house elevation in New York is using what is known as a "Power Pack".  A power pack is simply a compact, lightweight, common pressure hydraulic pump that is used to operate crib jacks to lift a structure.  The use of a power pack to lift structures requires a bit more skill compared to using a unified hydraulic jacking system.  With a unified system, all the jacks extend at the same rate and extend the same distance.  However, with a common pressure system, a jack which is lifting more weight would tend to extend more slowly than a jack lifting less weight.  More judgement is necessary in the placement of the crib jacks under the building, and a slightly different lifting procedure is used.
The theory behind building lifting with a power pack is somewhat the same as is behind the use of hydraulic transport dollies.  If four crib jacks are used, they are tied together into three zones.  In our example of a house elevation using a power pack, we will number the jacks 1, 2, 3, and 4.  First, each of the jacks is extended slightly so that the entire weight of the house is resting on the jacks.  We then take the pressure readings off of the jacks and find them as follows:

• Jack 1 - 3,500 psi
• Jack 2 - 3,800 psi
• Jack 3 - 3,645 psi
• Jack 4 - 3,655 psi

Now, because Jack 3 and Jack 4 are the closest in pressure, we will zone them together so they have common pressure.  Therefore, we will have three zones; Jack 1 = Zone 1, Jack 2 = Zone 2, Jacks 3&4 = Zone 3.
We will begin our lift by opening the zone valve that controls Zone 3 and moving the power pack control toward raise.  Jacks 3 & 4 will begin to extend.  Once they have extended approximately 8" (halfway extended), we will close the zone valve for zone 3, but leave the individual jack valves open so that fluid can flow between the two jacks. We then open the zone valve for Zone 1.  Jack 1 will begin to extend, rocking that corner of the house upward.  Jacks 3 & 4 will compensate for this rocking motion so that the house does not rack.  At the same time, we can also open the zone valve for Zone 2, adjusting the valves for Zone 1 and Zone 2 so that the two jacks travel at approximately the same speed.  Because jacks 3 & 4 are common pressure on the same zone, they will compensate for any difference in the speed at which jacks 1 & 2 extend.  After jacks 1 & 2 are fully extended, they can be blocked off with cribbing and jacks 3 & 4 extended the rest of the way.
Buckingham Structural Moving Equipment offers a customized Enerpac Power Pack with a zone package standard, as well as various used power packs.  Buckingham's used house moving equipment page currently shows a Modern Hydraulics jack pump for sale.