the invention is normally used in connection with power driven trolleys which ride on a main rail and carry suspended beef carcasses . a rail 2 and trolley 4 are shown in a very abbreviated form in fig1 and they carry carcasses such as the carcass designated 6 . the improved sidepuller includes a main frame 8 which moves parallel to the beef rail 2 so that the sidepuller will travel in the same direction and velocity as the moving carcasses . a vertically movable frame 10 is supported by the main frame 8 , and it carries a back support means 12 , pulling means 14 and 14 &# 39 ;, carriages 16 and 16 &# 39 ; which serve as support members , and moving means 18 and 18 &# 39 ; which move the carriages laterally as will be described later in this specification . the back support means 12 includes a backrest 20 which engages the back of the carcass during the hide pulling operation . it can be forced against the carcass by means of a hydraulic cylinder 22 which is mounted on a plate 24 attached to the frame 10 . the hide - engaging grippers 26 and 26 &# 39 ; are mounted on hydraulic cylinders 14 and 14 &# 39 ; which act as the pulling means . the grippers 26 and 26 &# 39 ; are used to grip the hide on opposite sides of the belly . small hide flaps are shown at 29 . each gripper includes a fixed jaw 30 and a movable jaw 31 which is actuated by a cylinder 32 in order to move the movable jaw from its open position to its closed hide - gripping position . the grippers 26 and 26 &# 39 ; are mounted on the rods of the hydraulic cylinders 14 and 14 &# 39 ; to pull the grippers and a hide gripped thereby in pulling directions that extend from the belly toward the back of the carcass . the cylinders have longitudinal axes 33 and 33 &# 39 ;, and the jaws of the grippers 26 and 26 &# 39 ; are positioned between these longitudinal axes so that the respective grippers extend toward each other and toward the belly of the carcass for convenience in gaining access to the flaps 29 . cylinders 14 and 14 &# 39 ; are supported at the rear of the frame 10 by carriages 16 and 16 &# 39 ; which are movable in arcuate tracks 28 and 28 &# 39 ;. such movement is produced by a pair of transversely oriented cylinders . only cylinder 18 is shown in fig1 for illustrative purposes , but both cylinders 18 and 18 &# 39 ; are shown in fig2 . these cylinders are the means for moving the pulling cylinders 14 and 14 &# 39 ; toward each other in an arcuate path which is lateral with respect to the hide pulling direction . the track is formed in two sections 28 and 28 &# 39 ;, each section being associated with one of the carriages 16 and 16 &# 39 ;. as shown in fig2 the track 28 is formed of an upper channel 34 and a lower channel 36 which are connected together by a plurality of stiffeners 38 . the carriage is a plate which carries eight wheels . each carriage has two upper wheels 40 , and each of these wheels has a diameter slightly less than the internal flange - to - flange distance of the upper channel 34 . two corresponding bottom wheels are provided on the carriage 16 to ride similarly in the lower channel 36 . each carriage 16 and 16 &# 39 ; also has four small wheels 41 which ride on the edges of the webs of the channels 34 and 36 . connector plates 42 are mounted on the forward portions of the carriages , and vertical pivot pins 44 and 44 &# 39 ; pass through these connector plates to connect the carriages 16 and 16 &# 39 ; to the pulling cylinders 14 and 14 &# 39 ;, and to the carriage - moving cylinders 18 and 18 &# 39 ;. additional details of the apparatus can be seen in fig3 where the members 46 , 48 , 50 and 52 of the main frame 8 can be seen . the frame 10 is vertically movable by a cylinder 54 which is connected to the member 50 of the main frame so that the grippers 26 and 26 &# 39 ; may be adjusted to a height suitable to the respective carcass . the main frame 8 is movable in the machine direction by the chain on the beef rail 2 . a cylinder 56 on the frame 8 is actuated to extend an indexing pin 58 into the path of a trolley on the beef rail . two longitudinally spaced indexing pins are preferably used . the main frame is supported on a pair of i - beams 60 which have elongated rods 62 of circular cross section welded to their upper flanges . the main frame 8 includes hanger assemblies 64 provided with rollers 66 with radiused grooves which correspond to the cross sections of the rods 62 . to resist lateral forces encountered during operation of the apparatus , the frame 8 has rollers 68 which ride on the mutually facing inboard surfaces of the webs of the i - beams 60 . at the lower end of the main frame 8 , pairs of rollers 70 are arranged to ride on opposite surfaces of vertical rail members 72 which are anchored to the floor . an operational cycle of the apparatus commences when the indexing pins 58 are extended into the paths of trolleys 4 so that the main frame 8 starts moving concurrently with a carcass 6 . if necessary , the frame 10 is moved vertically by cylinder 54 to locate the grippers 26 and 26 &# 39 ; at a suitable height for the carcass or carcasses being handled . the backrest 20 is in contact with the back of the carcass . the operator places the hide flaps 29 between the jaws of the two grippers 26 and 26 &# 39 ;, and actuates the cylinders 32 and 32 &# 39 ; to close the grippers . then , the backrest cylinder 22 , the pulling cylinders 14 and 14 &# 39 ; and the carriage - moving cylinders 18 and 18 &# 39 ; are actuated simultaneously so that the grippers 26 and 26 &# 39 ; and the hide gripped thereby are pulled from the belly toward the back of the animal . the backrest moves to the position shown in broken lines in fig1 . due to the action of the carriage - moving cylinders 18 and 18 &# 39 ;, the angulation of the hide pulling cylinders 14 and 14 &# 39 ; changes during the pulling movement . the pull is directed toward points established by the pivot pins 44 and 44 &# 39 ;, and these points move toward each other during the pulling action . although one embodiment of the invention has been shown and described in this specification . persons who are familiar with the art will realize that it is capable of taking many forms . therefore , it is emphasized that the invention is not limited solely to the disclosed embodiment but is embracing of modifications and variations thereof which fall within the spirit of the following claims .