112 as shown in fig1 and 11 to alternately disengage engagement pins 66 70 from pole flange 38 the vertical spacing of ramps 116 118 allows the vertical load on the jack to be supported by extended lower engagement pin 66 while upper ramp 118 causes upper engagement pin 70 to retract from the pole flange fig1 as the operator releases the downward pressure on jack lever 36 the jack moves down the pole when upper engagement pin 70 moves closer to lower engagement pin 66 the lower ramp 116 contacts horizontal engagement pin 66 through follower pin 111 to urge engagement pin to the right as viewed in fig1 however since the pin 66 supports the load on the jack frictional engagement between pin 66 and post flange 38 prevents retraction of engagement pin 66 forcing ramp guide upwardly against the bias of tension spring 110 so that contact between upper ramp 118 and follower pin 112 is removed as shown in fig1 allowing upper engagement pin 70 to re engage a hole 39 in pole flange 38 as the pin 70 moves into alignment with the next lower hole position the operator at this time reverses the pivotal travel of lever 36 so that the jack load shifts to upper engagement pin 70 the lower ramp 116 causes the lower engagement pin.