THE POLK SYSTEM 33 



Our System 



IN the development of our machine we have kept two things in 

 mind ease of ^Deration and the erection of an absolutely flaw- 

 less structure. Neither pains nor expense has been spared to 

 produce a machine that will enable you to put up as good a silo as 

 our best workmen can erect. Our machine automatically keeps 

 the walls plumb, it does away with an elaborate, complicated, 

 risky system of scaffolding, it imposes no strain upon the section 

 of wall already built, and it so unifies and simplifies the work 

 that any intelligent man, after seeing one silo constructed, can 

 easily erect the best silo on earth. 



As usual, the thing that makes all this possible is a very simple 

 thing after all. So simple indeed is it, that you will wonder why 

 other builders of concrete waste time, money and labor on costly 

 dangerous scaffolding. The great unifying, simplifying principle 

 in our machine is the use of a centermast. This centermast is 

 erected in the center of the silo floor and is guyed to a perpendi- 

 cular at the top by means of wires and turn buckles. It is a four 

 inch pipe, provided with a series of transverse openings adapted 

 to receive a key which supports a widely flanged collar, the latter 

 serving to support jacks by which the forms are lifted. Resting 

 upon the jacks is a hub, consisting of a flanged base collar and a 

 top dished collar connected by a central pipe of sufficient bore to 

 work easily over the centermast. On the base collar of the hub 

 radiate T irons which are supported from the upper collar by 

 tension bars. The T irons are rigidly clamped to the top edge of 

 the inner and outer forms, which are made of sheet metal. Each 

 form is composed of separable sections which have angle iron 

 edges. The separable sections are connected by threaded studs 

 which pass through alining apertures formed in the opposite 

 angle irons. The outer forms are bolted together and the inner 

 forms carry a wedge between each segment, the lifting of which 

 will allow the forms to swing free. 



They are not built of pieces and they 

 cannot go to piece*. ' ' 



