An  offset, extreme low clearance heavy lift jack

abstract:  a jack for lifting heavy furniture  with low clearance

This project was inspired by the need to move a piano, from one room to another.  A good upright piano may weigh something in the order of 500kg. For some arcane reason they are fitted with castors which is all well and good, but why are the castors so outrageously small??? They are allways so small that they dont turn and even if they spin the immense compressive force will score a timber floor and tear even heavy carpet.  What precisely is their point ?  I suppose that simple mechanical engineering is not a signifcant part of the piano builders craft. However, be that as it may, pianos still require to be shifted from one room to another !

In the past  , when I was younger and more foolish, I could just barely lift one end of our piano just long enough and high enough that she-who-must-be-obeyed could slip a thick pipe  under the piano  so it could be rolled.  Then would begin a song and dance with lever and blocks to get it high enough to slip a trolley underneath...a very foolhardy thing.

This jack acts like a fork lift and has low enough clearance to get under underneath and lift a piano or other heavy furniture high enough to safely insert a trolley.

The formerly automotive jack was recovered from a council hard rubbish collection. The new feet and the fork where made from quarter inch steel  and welded with the welder-o-doom.   The only preparation required is to remove the surplus metalwork from the jack, they may be some arrangements at the top, either a swivel or grab,  these arrangement must be removed and the fork welded  securely to the middle pivot piece.  I first made this device without the jack feet but found the tendancy of the load to rotate the jack was too extreme. The feet really are required.

In use, care must be taken not to overload the jack because the forces on it are not symmetrical and the forces will try to bend the jack through its end pivots which are not designed for this kind of loading. The load must be as close to the jack as possible to mitigate the turning moment on the jack end pivots.

I shouldnt have to say it, but will anyway. Dont use use this without inserting some solid object beneath the object being lifted.


dont test jack with remaining good limb!


page created Fri Feb  5 18:49:12 EST 2010