gpm to produce max torque of 5 400 ft lbs a motor of this type should be operated within the following ranges with the tool gpm gpm psi rpm motor psi motor tool tool tool torque differential 200 190 47 56 23 900 4 000 100 500 300 285 104 86 55 900 4 000 100 500 400 380 187 113 45 900 5 400 100 700 500 475 293 143 77 900 5 400 100 700 600 570 422 169 113 900 5 400 100 700 650 617 494 186 130 900 5 400 100 700 these psi 39 s are gained by using a total tfa of 0 884 one 24 jet one 24 jet and 11 as mud wt the casing cutter 10 may be any casing cutter that is known in the industry a suitable casing cutter 10 is shown in fig8 the casing cutter 10 has retractable blades 11 for cutting the casing fig8 also shows embodiments of a mud motor 20 a long stroke bumper jar 30 a spear 40 a bumper jar 50 drill pipe space out 9 and drill collar 8 referring to fig9 an alternative embodiment of the invention is shown for cutting downhole casing this embodiment of the invention is similar to those previously disclosed except that the cut retrieval tool 7 does not comprise a seal assembly retrieval tool rather the cut retrieval tool 7 only comprises a bumper jar 50 a spear.