Elevator Mechanic Exam

A Latching relay: Used for call registration,direction selection or as selector relays Two types are: Set/Rest are electrical and Mechanical Latching relays Need to know latching relay symbol, Its a box with shaded triangle in lower right hand corner. - Which relay do you need to Order 710 Pg, 7 RPM = 60 ∙ ƒ ÷ P÷2 = Step 1. 60 x Frequency (Hz.) = Step 2. Poles ÷ 2 = Take answer 1 and ÷ by answer 2 = - Know the formula for RPM 435 Pg. 5 If you are referring to a megohm meter, it is a test of the insulation properties of such things as electric wiring, motor windings and high power antenna mounts. We use a "megger" or "meg out" electrical wiring and equipment to see if it is shorted to ground or the frame in any way. The megger uses much higher voltages to check resistance than a normal Volt-ohm meter. Minimum resistance is 1 Meg Ohm - Know what a Megger is and what it does 636 Pg. 13 (1) A parallel connection. (2) A resistive element placed across the terminals of an armature to bypass a portion of the current. (3) A flexible electrical conductor designed to conduct current around the mechanical joint between two conductors. (4) The resistive element (Usually of very low resistance) used in parallel with a DC ammeter movement to bypass a calibrated portion of the total circuit current. - Shunt Overloads 425 All Pages Bad Ground - You are using a Temp Run Box and you get shocked! Why! 520 Pg. 4 The bridle hitch can consist of two,three, or four single hitches (fig. 3-22), used together to form a bridle hitch for hoisting an object A sling with two legs used to lift a 1,000 pound object will have 500 pounds of the load on each leg when the sling angle is 90 degrees. The load stress on each leg increases as the angle decreases; and if the sling angle was 30 degrees lifting the same 1,000 pound object, the load will be 1,000 pounds on each leg. Try to keep all sling angles greater than 45 degrees; sling angles approaching 30 degrees are considered extremely hazardous and must be avoided at all cost. - Bridal Hitch 128 Pg 17 Scaffolding should be tied to the structure using #9 wire or tie-in devices. The first vertical tie should be at the maximum height of 4 times the narrowest base dimension. Additional ties are not to exceed 26' vertically. Maximum horizontal distance between ties is not to exceed 30'. - Scaffolding, You have 32' of rise, you are using 3x5 scaffolding. Where will the tie off points be ? 140 PG. 287-288 Counterweights (Typically) are hung to counter balance the weight of the car PLUS 40% of Capacity Load. - How much should Counterweight way? 240 Pg. 14 Note: We do not use wire smaller than #20 in travelling cables and #24 outside travelers. Largest wires are feeders to Hoist /Pump motor We always have 10 % spares 10% of 52 = 5.2 On a calculator Multiply the percent 10 by the number you have and ÷ by 100 10 X 52 ÷ 100 = 5.2 - Pulling Spare Wires (Example) 10% of 52 Wires 515 Pg.26 The correct lube must be used on chains. - The freight door motor is spinning but the door wont move, Why? 535 Pg. 9 Lula: Limited use/Limited Access (Example Wheelchair Lifts) Max Rise 25' Max Speed 30 Ft/Min Max Capacity 1400 Lbs. Max Platform Area 18 Sq/Ft. Residential Elevator: Max Rise 50 ' Max Speed 40 Ft/min Max Capacity 940 Lbs. Max Platform Area 19 Sq/Ft 840 Pg 2 Dumbwaiters: Platform limited to 9 Sq/Ft Inside height is limited to no more than 4 Feet Capacity is limited to 500Lbs No Riders - Read Lula and Dumb waiters 545 Pg 1 You never get on top and you work only partially in with the main line OFF - If you get on top of Dumbwaiter what must be done? 545 Pg 14 Notes:(Pi) π is 3.1416 and 231 Cubic inches to the Gallon Area: Remember to ÷ 6" ÷ 2 = 3 to get Radius Area = π∙ r² Area = 3.1416 x 3 x 3 = 28.27 inches or 3.146 x 9 = 28.27 Volume Multiple are times height to solve for Volume V = A∙H V = 28.27 x 300 (25" feet x 12" = 300) V = 8481 Cubic Inches Since we already know there are 231 cubic inches to the gallon 8481 ÷ 231 = 36.71 Gallons - PSI Formula and Gallons (Example) How much oil to move a 6" jack 25' 815 Pg 10 Relief Valve : Must be tested Annually Its is simply Pressure relief (If car strikes obstruction,Overloaded Car,Car hits stop ring) If set to light Car may not move! Check Valve: It is simply a one way valve permitting oil to flow in one direction Up Valve: The most complicated valve in system Controls Up Start and acceleration to high speed, up slow down, up leveling speed, and up stopping. Down Valve: Because the elevator is not running when on the down direction the down valve depends on system pressure. Bypass and Relief Valve: Have been combined into one - Valve Operation 815 Pg 16,17 Simply: In a Inverting Op Amp (INPUT) is supplied to the Negative In a Non Inverting Op Amp (INPUT) is supplied to Positive - Amplifiers (Inverting and Non Inverting) 640 Pg 11 Minimum is 2 switches 15 lbs. and must stop the lift within 2" - In a vertical lift how many sensors are required (Pan Switches) 845 Pg Unknown SCRs are used in DC door motor control and more commonly in Direct Drives (Replacing DC Generators) SCR is a three terminal device. It basically acts as an on/off switch by pulsing the gate of the SCR with a positive voltage. Once an SCR is turned on it remains on, till anode and cathode voltages equalize or the anode and cathode are reversed biased or voltage is removed from the anode and cathode. - SCR's 635 Pg12 A Meter with the positive lead on the Anode and the negative lead on the Cathode. A jumper is placed across the Anode and Gate as well This should show .7 Volts an indication of a Good SCR - SCR Example: 635 Pg 14 Figure 26 In this figure 11 (Pg 7 Unit 625) it shows R¹ which controls the rate that the magnetic field builds.