By way of summary, the present invention cont•。m- plates a nov•l method of grooving a hoisting drum of any suitable type wherein a “master  cylinder” may  be utilized to provide a variety of counterbalanced grooving systems。 The “master cylinder” comprises a sleeve which may be machined in any well i:nowt manner to  provide  a  plu- rality  of  para11。•l yooves  on the  outer periphery  ‘thereof。

Tbis type  of  machining  operation  is  well  known,  and  may   d0

be  accomplished  by  the  usual  lathe,  milling  machine, or

the likc, thus eliminating the necessity of: specially de- signed adapters in the construction of the grooved sleeve。 The parallel grooved sleeve niay tIi•n be cut or slit to provide a plurality of arcuate sections or segau•-nts, and portions or the segments  may  be  re-in。anged  and welded or bolted, or th• lit:e, to the  outer  periphery  of  a drum cGre in order to provide a continuous helical and parallel groove thereon。   The same method of grooving may   be

utilized  to provide  substantially  any  continuous  combined 60

helical  and parallel  groove  on  a  drum,  with  only the cut-

ting of tbe sleeve differing in accordance with the par- ticular  grooving  design desired。

Fro:n the foregoing, it will be apparent that tn"e present invention  provides  a  nov»•1  method  for  groo•/ing  a  spool-  65

ing  drum,  or  the  like,  in  a manner  utilizing conventional

machining devices, and greatly reduces the  cost  and ti。me of manufacture  of  counterbalanced  grooving  on the drum。

A  variety  of:  the  types  of  continuous  circumferential grooves comprising comliined helical and straight or paral- 70 lel portions  may  be provided  。on  a  drum core  by  using a

“master cylinder” or parallel grooved drum。 The novel grooving method is simple and efficient in operation and economical  and  durable  in construction。

Whereas,  the  present  invention  has  been  described  in

particular relation to the drawings  attached  hereto, it shoald be understood that other and funher modifica- tions, apart from those  shown  or  suggested  herein, may 'be made  within  the spirit  and scope  of  this invention。

What is claimed is:

1。A method of providing a  continuous  oircumferen- tial groove having alternate  helical  and  parallel sections on a  drum  core,  and  consisting  of  providing  a plurality of grooves on the  outer  periphery  of  a  sleeve, severing the yooved Sleeve into a plurality of segments, and in- terchanging certain pairs of the shivered segments and securing the interchanged pairs and the remaining seg- ments on tire outer periphery o:I  the  drum  core  to pro- vide the continuous alternate helical and parallel circum- ferential groo-ze。

2。A method of pro•/iding a  continuous  circuinferen- tial groove having alternate  helical  and  parallel sections on a diam  core,  and  consisting  of  providing  a plurality of parallel grooves on the outer periphery of a sleeve, severing the parallel grooved sleeve into a plurality of segments, intei chan%ng certain of the seveied se,•ments, and secaring the  int-•rchanged  and  remaining  segments on the outer periphery of the dixim core to provide bh-• continuous a1terno。te helical and para11e1 circuit。ferential groove,  and  securing  the  segments  to  the  drum  core。