When extension members adjacent each end of the overall conveyor module are each in a first retracted position and,10 for example, the outer and inner support structures are aligned for the inclusion of one or more shared rollers, the overall length of the module is equal to a whole-number multiple of the predetermined roller spacing plus some first constant. In various versions, each extension member   is 15 extendable beyond the free end of the support structure from which it depends by a distance equal to at least one-half the predetermined roller-axis spacing so that the overall length of the conveyor module can be extended, without translating the inner support structure with respect to the outer support 20 structure, by a length at least as long as the predetermined roller-axis spacing. It will be appreciated that a conveyor module has some maximally retracted length in which some maximum number of rollers is shared and the extension members are fully retracted and some maximally  extended 25 length in which some minimum number of rollers is shared and the extension members are maximally extended. It will furthermore be appreciated that when each extension mem- ber is adapted for selective retention in any position between its first retracted position and a second extended position 30 corresponding to an overall increase in the length of the support structure of at least one-half of the predetermined roller-axis spacing beyond the minimum assumable length of the support structure from which in depends, the conveyor module  can be  adjusted  to  assume  any  overall length 35 between its maximally retracted and maximally extended lengths.

BRIEF DESCRIPTION OF THE DRAWINGS

40 FIG. A depicts an illustrative fixed-length power roller conveyor module;

FIGS. B and C illustrative one particular difficulty encountered with fixed-length conveyor modules;

FIG.  1 depicts  an  illustrative   adjustable-length   roller 45  conveyor module;

FIG. 2 is an enlarged view of an extension apparatus on the conveyor module of FIG.  1;

FIG. 3 depicts as illustrative dual-support-structure roller conveyor module; and 50

FIGS.  4A  through  4D  schematically  illustrate various degrees of extension, and the corresponding number of shared rollers in each of four positions, of the inner support structure with  respect  to  the outer support structure  of an 55  illustrative dual-support-structure  conveyor module.

DETAILED  DESCRIPTION

The following description of various embodiments of a roller  conveyor  module  is  illustrative  in  nature   and   is 60 therefore not intended to limit the scope of the invention or its application of uses.

Referring to FIG. 1, an adjustable roller conveyor module 15 includes a roller support structure 20. The roller support structure  20  includes  first  and  second  laterally   spaced,

65 elongated frame members 22 and 24 arranged in parallel and extending along a longitudinal axis Ag. Each of the first and second frame members 22 and 24 has a first end 26 and a

second end 28 coinciding with, respectively, first and second ends 30 and 32 of the roller support structure 20. Extending between, and supported by, the parallel frame members  22 and 24 is a plurality of rollers 40. In a typical embodiment, each roller 40 rotates about a roller axis 42 that extends 5 perpendicularly to the central longitudinal axis and parallel

to the axes 42 of other rollers among the plurality. Furthermore, in a typical version, the axes 42 of the rollers 40 supported by the support structure 20 lie along a roller

plane  and  are spaced equally  in accordance  with  a prede- 10

termined roller-axis spacing constant.

The roller support structure 20 further includes extension apparatus 50 adapted for extending the overall length of the conveyor module 15. The illustrative version of FIG.  1 includes extension apparatus 50 reciprocably depending 15 from the support structure 20 and adapted for selective positioning beyond each of the first and second ends 30 and