Hydraproducts manufactures micro hydraulic packs, the smallest of which is the unidirectional pack at 87mm square. These tiny hydraulic motors are often used in brakes and clamps, for mobility equipment such as powered wheelchairs and lifts, where space is at a premium but the power output still needs to be high enough to effect the actions required; up to 5 LPM.
Reversible micro packs are also available, although they are slightly larger, given that they must operate in two directions. Where the unidirectional packs use gravity to return back to their original position using solenoid and check valves, the reversible models use hydraulic flow to effect movement in both directions. These are often used in applications where tension is to be achieved across a component, or where fine positioning is very important, as the double direction movement can be tuned to exact position required. Common uses include mobility products such as lifts and wheelchairs; as well as bath lifts and other lifting equipment that needs to lower and rise within the same unit.
The reversible power packs are also available mounted to a cylinder for complete actuator manufacturing, and come with a selection of mounting plates for easy installation within whatever apparatus requires dual-direction hydraulic motion. These kits are also fitted with manual override function and have thermal relief valves, to release excess pressure from overloading or thermal expansion, which the solo units do not.
YouTube user maskinsmidjur has created, what seems to be, the world’s smallest hydraulic bottle jack, which he claims is capable of lifting up to 1100 kg – a video he posted, shows him using the tiny jack to lift one side of his car. The jack itself is just over an inch tall and functions exactly as the standard sizes do. He made the jack himself and has other videos showing his miniature creations, which include a crossbow and bear trap. Unfortunately, the mini hydraulic jack is not available to buy, which is a real shame as it would make a perfect present for a hydraulic engineer or mechanic. Recreating this jack would take some real skill and dedication to make something this small, and perhaps this is the preserve of miniature model enthusiasts. It would certainly make a great addition to a scale model of an automotive workshop and would even come in handy for propping up loose hanging doors, as it would slide in easily underneath.
The smallest genuine hydraulic jack we could find is this bottle jack, from SGS Engineering. Capable of lifting up to 10 tons it operates at 700 bar with a 9.1 ton load, and lifts from 120mm to 149mm. The jack can be used vertically and horizontally and is a versatile little piece of equipment that would be very useful in many industries, as it is small enough to slide into very narrow gaps. There are models of hydraulic jacks available for remote control car enthusiasts, and they might make a good conversation piece in a workshop office, but many of these models actually use a spring mechanism to mimic the movement, rather than real hydraulic technology.
Building one of these tiny jacks would be a great project for getting would-be engineers into the world of hydraulics and understanding how they work, as well as the many applications of hydraulic technology and the equipment it is used in. With access to metalworking equipment, a very small hydraulic jack could be fabricated using the micro packs from Hydraproducts and some sheet metal, resulting in a very impressive science project for budding engineers or a nice conversational piece for hydraulically minded people.