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         outer sleeve 222A, 222B; inner sleeve 242A, 242B; and the
         pair of seals 244A 244B to a source of compressed air. The
         compressed  air  is  maintained  at  a  pressure  sufficient  to
         purge the space and to prevent accumulation of dust and de-
         bris within the space. The sealing members can be o-rings
         formed of PTFE, EPDM, butyl rubber, or other suitable mate-
         rial. Each engaged set of outer sleeves 222A, 222B and inner
         sleeves 242A, 242B form an extendable tube 220A, 220B that
         each defines a section of inflow and outflow conveyor tubes 16
         and 18 respectively. It should be appreciated that extendable
         tubes according the present invention can be formed directly
         from the inflow and outflow conveyor tubes 16 and 18 that are
         attached to the upper housing 12 and the infeed housing 14.
           A pneumatic actuator 262 is positioned between the tubes
         220A, 220B and is connected to flanges 202A, 202B at oppo-
         site ends. Movement of pneumatic actuator 262 causes move-
         ment of flange 202A relative to flange 202B and thus move-












                                                              Figure 8: Tension control apparatus, wherein the tension control ap-
                                                              paratus is in second position.
                                                              tubular portion 54 is connected with inlet tube 48 via the pas-
                                                              sageway  of  second  extendable  tube  220B.  Similarly,  upper
                                                              end 66 of outlet tube 62 is connected to second flange 202B
                                                              at an opening such that inlet tube 48 is axially aligned with
                                                              the passageway of first extendable tube 220A. Lower end 69















         Figure 7: Partial front view of the tension control apparatus, wherein
         the tension control apparatus is in a first position.

         ment of the tubes 220A, 220B. The pneumatic actuator 262
         is connected to a source of compressed air 263 that can be ad-
         justed to a predetermined pressure via a pressure regulator
         264. Tubes 220A, 220B can thus be extended and retracted
         by varying the air pressure applied to the pneumatic actuator
         262, and tubes 220A, 220B can be held in a desired position
         by maintaining a constant air pressure with pressure regula-
         tor 264 when the tension on rope assembly 40 is constant. In
         this regard, the air pressure of pneumatic actuator 262 is a
         signal indicative of tension in rope assembly 40.
           Tensioning assembly 200 is positioned between upper hous-
         ing 12 and lower housing 14 of aero-mechanical conveyor 10.
         Referring again to figure 6, upper end 52 of the inlet tube 48
         is connected to second flange 202B at an opening such that
         inlet tube 48 is axially aligned with the passageway that ex-
         tends through extendable tube 200A. End 55 of first upper
         tubular portion 54 is connected to first flange 202A such that   Figure 9: Partial side view of the tension control apparatus.

         60     Wire Rope News & Sling Technology   August 2017
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