7.3.9 Step Upthrust Device
Test the step upthrust device, (See Figure 7-16) for escalators installed under the 1980
supplement and later editions of the Code, as follows:
a. Barricade the escalator to prevent access by unauthorized persons.
b. Stop the escalator, open the mainline and remove one or more steps. After this test a
thorough examination of the interior of the escalator can be made before the steps are installed.
c. Run the escalator until the step above the missing one is located on the lower curve and
then stop it by pressing the stop button.
d. Open and lock out the main disconnect switch to remove all power and remove the
controller from the escalator truss.
e. Connect a circuit continuity tester, such as an ohmmeter, across the safety control circuit. If
all safety devices are set correctly, there will be continuity in the circuit.
f. Depress the emergency stop button and check the circuit continuity tester to see if the
continuity was broken when depressed and reestablished when the button was released. This will
confirm that the stop button is part of the safety circuit and functioning properly.
g. Lift up on the riser of the step located on the lower curve so that the step comes into contact
with the upthrust tract. Determine that the safety circuit continuity is broken and is reestablished
when the step riser is released. This will confirm the mechanical integrity of the upthrust
device as well as its electrical function with the electrical control circuit.
h. Since the emergency stop button was used earlier to stop the escalator, and its operation
was checked to confirm that it, like the step upthrust device, breaks the continuity of the safety
circuit, the ability of this circuit to remove power from the escalator motor and brake has been
i. Remove the circuit continuity tester and replace the controller and step.