hole 215 and back into the oil storage member 1 via an inlet 12 thereof the state of forward movement of the oil pressure tank is shown in fig1 b and 14 wherein the handle is moved toward a side so that the oil from the inlet 11 of the oil storage member 1 flows into the oil pressure tank 3 via a first oil passage 22 as shown in fig1 to push the piston 31 of the oil pressure tank 3 outward accordingly the axial shaft 41 connected at the end of the piston rod 32 is also pushed outward as shown in fig1 at the same time when the pressure of the oil flowing into the oil pressure tank 3 reaches a maximum value the oil will flow through an oil chamber 33 inside of the piston rod 32 to a second oil passage 23 as shown in fig1 and then flow through a third oil passage 24 into the return passage 213 and finally flow back into the oil storage member 1 via a fourth oil passage 25 at one end of the inlet 12 the forward movement of the oil pressure tank 3 can perform external pulling operation for the object 7 to be disassembled as shown in fig3 4 and 4 a the state of backward movement of the oil pressure tank is shown in fig1 c and 17 wherein the handle is moved toward another side so that the oil from the inlet 11 of the oil storage member 1 will flow into a sixth.