| 主权项 |
1. A roof ladder construction comprising:
a roof hook assembly; a ladder to which the roof hook assembly is pivotally mountable for movement between two operative positions, the ladder comprising i) stiles, the stiles each having a hollow rectangular cross section with two opposite side walls, and ii) rungs, the rungs extending through each of the two opposite side walls of each stile, maintaining the stiles in fixed, spaced apart arrangement, a first of said operative positions being a position in which the roof hook assembly may extend over a roof ridge for engagement with a remote roof surface at a side of the roof opposite that at which the ladder is positioned, and a second of said operative positions being another position in which the roof hook assembly does not engage with said remote surface of the roof, wherein movement of the roof hook assembly is remotely controllable, wherein a control member for remote control of movement of the roof hook assembly extends through a hollow portion of one of the stiles, and wherein the control member extends through the one stile from a top end of the one stile adjacent the roof hook assembly to an opposite end of the one stile which is remote from the ladder end region at which the roof hook assembly is pivotally mountable; a remotely controllable locking element for securing the roof hook assembly relative to the ladder in at least one of the two operative positions; and a remotely extending actuation member, wherein the actuation member extends through an associated stile for remote control of said locking element, wherein the actuation member extends through the associated stile to an end of the stile which is remote from the ladder end region at which the roof hook assembly is pivotally mountable, wherein said actuation member comprises a resiliently loaded member; and resilient bias means to hold the remotely controllable locking element in position to secure the roof hook assembly relative to the ladder in at least one of the two operative positions, wherein the locking element comprises a pin displaceable in a locking direction to a locking position by the resilient bias means and displaceable against the bias means to a non-locking position by the actuation member, and wherein the actuation member comprises i) a cord which extends lengthwise within the associated stile and connects with the pin, and ii) a cord clutch that locks and unlocks movement of the cord, the cord clutch including an operating lever moveable between a cord engaging position in which the cord clutch prevents movement of the cord and a cord release position in which the cord clutch allows the cord to move lengthwise within the associated stile. |
