the frame body 1 via a tail end axle so that in this manner the saddle 2 canbe driven to move upwardly or downwardly for lifting things by the pushing force from the ram plunger 33 of the hydraulic cartridge 3 hydraulic cartridge 3 has structure similar to a traditional one therefore its details are omitted the hydraulic cartridge is joined to the axle rod 32 located under the lifting arms 23 as shown in fig1 and 2 for driving the lifting arms 23 and connecting rods 22 to move upwardly or downwardly the bottom end of the hydraulic cartridge 3 is provided with a semicircular cylindrical base 31 which extends toward bothits left and right side so that in this manner it can be fitted into the semicircular grooves 113 of the drive brackets 112 also its width is about the same as the distance between the two side boards 11 of the framebody 1 in addition to the present invention being applied to the above trolley type hydraulic jack it can also be applied to other types of hydraulic jack fig3 and 4 illustrate another embodiment of the present invention whichis a portable 4 wheel hydraulic jack with the hydraulic cartridge 4 mountedin vertical position on the inner sides of the two vertical side boards 16 at proper locations they are also provided with respective drive brackets 112 and their semicircular grooves 113 are orientated in a substantially upward direction depending on the positioning.