Section 3.17 Car Safeties, Counterweight Safeties, Plunger Gripper, and Governors
If an auxiliary pump is used to move the car in the up direction to release the safeties, it shall
(a) have a relief valve that limits the pressure to not more than 2.3 times the working pressure
(b) be connected between the check valve or control valve and the shutoff valve
A plunger gripper shall be permitted to be provided for direct-acting hydraulic elevators using hydraulic jacks equipped with plungers. A plunger gripper shall be capable of stopping and holding the car with its rated load from the actual measured tripping speed per Table 22.214.171.124 and shall conform to 126.96.36.199 through 188.8.131.52. In Table 184.108.40.206 the words "rated speed" shall be replaced by "operating speed in the down direction."
(a) the external pressure applied to the plunger by the device is symmetrically distributed at locations around the circumference of the plunger. The resulting stress in the plunger shall not exceed 67% of the yield strength at any point of the plunger.
(b) the external pressure applied to the plunger by the device does not exceed 67% of the value that will cause local buckling. Where the external pressure is applied over substantially the full circumference of the plunger, the maximum value shall be permitted to be determined by 220.127.116.11.
(c) during the application, the plunger and the plunger gripper are capable of withstanding any vertical forces imposed on them, and transfer such forces to the supporting structure. During the application of the device, any loading on the plunger shall not damage the cylinder.
(d) power is removed from the hydraulic machine before or at the time of application.
(a) The plunger gripper shall be fully operational during a primary electrical system power failure.
(b) The elevator shall not be permitted to restart after a normal stop in the event of a failure within the electrical means used to actuate the gripper of any of the following:
(1) a single mechanically operated switch
(2) a single magnetically operated switch, contactor, or relay
(3) a single solenoid
(5) the software system
(6) the occurrence of a single ground
(a) The average deceleration rate at rated load shall be not less than 0.1g, where g is gravity, nor more than 1.0g. (See Nonmandatory Appendix P for minimum and maximum stopping distances.)
(b) Any peak deceleration rate in excess of 2.0g shall have a duration not greater than 0.04 s.
(a) that it is a plunger gripper.
(c) the maximum load in newtons (pounds-force) for which the gripper is designed and installed to stop and sustain.
(d) the manufacturer's name or trademark and identification number of the device.
(e) space for the date of the acceptance test. The date shall be permanently marked following the test.
(f) the diameter and minimum wall thickness of the plunger for which the device is applicable.