VG OSG
Version 3
7
A modern digital governor and tension weight to complement and integrate with
the VG range of safety gears and the VG rope brake.
The governor incorporates a drop-jaw mechanism which produces the same
operating force in both “up” and “down” directions. This can be varied to suit the
application.
The governor has an integral electric actuator to reset the governor remotely.
The governor can have an independent pulse encoder fitted for integrating with
lift control systems.
The digital control system permits a wide range of speeds to be selected
with a superior accuracy over mechanical systems. The control system has a
programmable feature for monitoring any form of uncontrolled lift movement
Specification
General Descriptions
Please refer to drawing “VG OSG General Overview – fig 8 pg 21” which illustrate
the mechanical assembly and the “Scott – Russell” linkage respectively.
The drop weight CDS1703 is pivoted on one end of links CDS01708 and pivoted
jaw CDS01716 at the other end. One end of short links CDS01707 are pivoted at
the centre of the long links and the other ends are anchored to the side plates of
the governor.
The drop weight is held in the disengaged position by a small dc magnet which
is released when an over-speed is detected. As the weight drops the pivoted
jaw is constrained to move horizontally and trap the governor rope against
spring loaded jaw CDS01713. The weight continues to drop until the long link is
horizontal.
The force generated by the governor is controlled by:-
1) The force exerted by springs in the fixed jaw
2) The profile of the governor jaws
The standard governor has a nominal braking force of 500 Newtons in both “up”
and “down” directions. This is generated by four compression springs CDS01722
and a 50% undercut “U” grooves in the gripping jaws. The braking force can be
increased by inserting two additional springs in the assembly and/or increasing
the width of the groove undercut.
Unlike friction governors, the mass of the tension weight and the governor rope
has no influence on the braking force. However, the weight requires a positive
lock-down feature to resist a pull in the “up” direction equal to the governor rated
force and be bolted to the pit floor or other steelwork.
The modular tension weight is shown in drawing “VG TW – fig 9 pg 21”. It
consists of a pulley assembly fitted with two sprung ratchets which engage with
a ratchet bar suspended from the tension weight frame. At least one ratchet is
engaged at all times to prevent the pulley from being lifted more than 10 mm.
The tension weight can have additional weights added to the pulley when used
with friction type governors. Other Tension Weights can be used as long as they
are fitted with a suitable lock-down feature.
To reset the governor, the drop weight is raised to its release position by an
electric actuator CDS01740. This is mounted adjacent to the drop weight and
operates against a sprung stop bolted to be drop weight. The linear actuator is
fitted with a potentiometer to verify that it is fully retracted before the governor is
placed back in service.
Brake Mechanism
