| 摘要 |
In a multiple extending section aerial ladder, a control linkage which allows the elevation, rotation and extension of the ladder to be controlled both from its base and from a working station on its top end. Two sets of rotatable tubes on the middle section of the ladder receive rotatable rods mounted on the upper and lower sections. The sets of rods and tubes rotate together, and each rod can extend out of and retract into its tube to accommodate extension and retraction of the ladder. The tubes in the two sets are connected in pairs by crank arms which cause the tubes in each pair to rotate together but in opposite directions. Hydraulic valves which control the ladder functions can be operated directly from the base of the ladder by hand levers on the lower set of rods. The valves can also be operated through the control linkage by handles on the upper set of rods.
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