Dewhurst
APPLICATION
The VL31 Gatelock is robustly constructed for installation on lift landings with single swing doors.
Operation is in accordance with BS5655 : Part 1 : 1986, except for Clause 7.7.3.1.1 and Appendix F.1.
For use as like-for-like replacement only, in accordance with BS5655 : Parts 11 & 12 : Clause 2.2.
ENVIRONMENT
VL31 is suitable for application in all normal indoor locations. Abnormal locations involving water spraying or splashing, chemical fumes and ignitable or explosive gases or dusts, require more detailed consideration. If in doubt concerning location or installation, consult the manufacturers.
OPERATION
The gatelock should be used in conjunction with a suitable retiring ramp. (Dewhurst Type FR21 is suitable for this application).
When the landing door is closed, the beak enters the lock and engages with an insulated cam which carries contacts that then complete a primary circuit (A). When the ramp clears the lock roller the operating arm of the gatelock falls forward allowing the locking plate to move downward, trapping the beak in position. The beak locking action is accompanied by the completion of a secondary circuit (B), but only if the primary circuit has been made.
