| 摘要 |
A heat sealing or heat welding apparatus for sealing lapped joints in laid up roof structures having an interchangeable drive for driving either or both of a pair of laterally spaced drive wheels and in which a heating element is selectively movable to plural operative positions including positions in alignment with the drive wheels whereby drive wheels perform the dual function of a traction drive and a pressure roll, and the drive wheels are able to traverse a path of travel coincident with that of the heating element during heat sealing of such lapped joints by the apparatus. The interchangeable drive and multiple operative positions of the heating element permit the apparatus to move forwardly for traverse of the lapped joint in either of the opposite directions of travel therealong.
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