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Special Equipment Operator (China) practice questions

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Question 1Lifting appliances, forklifts and actual load-control models

Which major structural component of a top-slewing tower crane carries the hoisting winch machinery, electrical control cabinets, and counterweight ballast blocks?

  1. The distribution trolley (*chariot de distribution*)
  2. The counter-jib (*contre-flèche*) Correct answer.
  3. The undercarriage chassis (*châssis de base*)
  4. The hook block (*moufle de levage*)

Explanation

The counter-jib (*contre-flèche*) extends rearward from the crane tower top or slewing ring. It houses the heavy counterweights (*lest de contre-flèche*), the main hoist winch, and electrical enclosures, balancing the overturning moments created by the forward working jib (*flèche*).

Question 2Lifting appliances, forklifts and actual load-control models

What is the primary mechanical function of the slewing ring (*couronne d'orientation*) on a tower crane?

  1. Allowing continuous 360-degree rotation of the crane superstructure while transmitting immense vertical loads and overturning bending moments into the mast Correct answer.
  2. Spooling the main hoist rope smoothly onto the winch drum
  3. Locking the crane jib in a fixed position during violent storm winds
  4. Measuring the dynamic weight of the suspended concrete bucket

Explanation

The slewing ring is a large-diameter heavy-duty bearing with internal or external gear teeth driven by one or two electric slewing motors. It must safely transmit the massive vertical, axial, and overturning bending moments from the jib and counter-jib down into the stationary mast while providing smooth rotational motion.

Question 3Lifting appliances, forklifts and actual load-control models

How is the horizontal movement of the distribution trolley (*chariot de distribution*) along the crane jib accomplished?

  1. By gravitational rolling controlled by friction disc handbrakes
  2. By hydraulic fluid pumped directly through telescopic jib cylinders
  3. By manual ropes pulled by the slinger on the ground
  4. By an electric trolley travel winch (*treuil de chariot*) driving opposing steel wire ropes connected to the front and rear of the trolley Correct answer.

Explanation

The trolley travel mechanism uses a dedicated electric winch drum that pulls continuous steel wire ropes routed through sheaves at the jib tip and mast, allowing positive mechanical travel both outward (*chariot avant*) and inward (*chariot arrière*).

Question 4Lifting appliances, forklifts and actual load-control models

What is the mechanical purpose of the sheaves (*poulies*) housed inside the hook block (*moufle*) and distribution trolley?

  1. To measure ambient air temperature aloft
  2. To lock the hook rotation whenever the wind exceeds 50 km/h
  3. To guide the hoist wire rope and provide mechanical advantage through multiple falls of reeving (*mouflage*) Correct answer.
  4. To inject lubricating grease continuously onto the electrical cables

Explanation

The sheaves in the trolley and hook block guide the steel hoist rope and form a pulley block system (reeving / *mouflage*). Reeving with multiple falls (e.g. 2 or 4 falls) provides mechanical advantage, multiplying lifting capacity while reducing line tension on the winch drum.

Question 5Lifting appliances, forklifts and actual load-control models

In a supplied ideal line-pull-limited model with unchanged rope speed and no other capacity limit, changing from two to four supporting rope parts doubles support and halves hook speed. Which listed change matches that stated model, rather than every real crane rating?

  1. Maximum lifting capacity doubles, while maximum hoisting speed is halved Correct answer.
  2. Maximum lifting capacity is halved, while maximum hoisting speed doubles
  3. Both maximum capacity and hoisting speed double simultaneously
  4. Capacity remains unchanged, but motor electrical power consumption is tripled

Explanation

In accordance with basic pulley physics, doubling the number of rope falls supporting the hook block from 2 to 4 doubles the mechanical advantage, doubling the crane's maximum allowable gross load (e.g. from 4 tonnes to 8 tonnes). In return, the hoist drum must spool twice as much rope to raise the hook by the same distance, halving the linear hook speed.

Question 6Lifting appliances, forklifts and actual load-control models

What is the primary safety purpose of the load moment limiter (*limiteur de moment / couple*) on a tower crane?

  1. Preventing the trolley from traveling backwards toward the mast
  2. Preventing structural collapse or tipping by automatically halting outward trolley travel and hoisting when the overturning moment reaches safe limits Correct answer.
  3. Preventing electrical short circuits in the generator set
  4. Limiting the maximum slewing speed during strong tailwinds

Explanation

The specified load-moment protective function responds to relevant load and radius conditions under the actual design. It is not a guarantee against every structural failure, ground problem, side force or incorrect configuration. Understand its actual behavior without bypassing it or treating the display as a complete lift approval.

Question 7Lifting appliances, forklifts and actual load-control models

How does the maximum gross load limiter (*limiteur de charge maximale*) differ from the moment limiter?

  1. It only operates when the trolley is positioned at the extreme tip of the jib
  2. It measures the wind speed acting against the counterweight blocks
  3. It cuts off power to the slewing motors during rotational acceleration
  4. It cuts off hoisting power immediately whenever the suspended mass exceeds the crane's structural maximum capacity (e.g. 6.0 t), regardless of radius Correct answer.

Explanation

The defined gross-load function addresses the selected maximum load condition, while moment-related limits also depend on radius and configuration. Actual stopping actions and settings are product-specific. Neither device alone establishes that all rope, hook, support, wind and structural conditions are suitable.

Question 8Lifting appliances, forklifts and actual load-control models

When the moment limiter (*limiteur de moment*) trips due to excessive load at a given radius, what automatic kinematic actions occur?

  1. All crane movements including slewing and lowering are permanently locked out
  2. The slewing brake disengages into free weathercocking while the load drops
  3. The hoist line is cut by an emergency pyrotechnic guillotine
  4. Hoisting up (*levage montée*) and outward trolley travel (*chariot avant*) are disabled; lowering (*descente*) and inward trolley travel (*chariot arrière*) remain enabled Correct answer.

Explanation

The listed movement restrictions correspond to the described product response to its load-moment condition. Actual controllers can differ, and not every enabled motion is automatically safe in the real situation. Follow the actual approved response and competent plan rather than improvise recovery from an overload.

Question 9Lifting appliances, forklifts and actual load-control models

What is the critical safety function of the upper hoist travel limit switch (*fin de course haut de levage*)?

  1. Stopping the upward motion of the hook block before it strikes the distribution trolley or jib structure, preserving a mandatory safety clearance buffer Correct answer.
  2. Preventing the hoist cable from unwinding completely off the winch drum
  3. Cutting off electrical power whenever wind speed exceeds 72 km/h
  4. Locking the hook safety latch automatically during hoisting

Explanation

The upper hoist limit switch (equivalent to an anti-two-block device) stops upward travel before the hook block crashes into the trolley sheaves (*choc sous chariot*). An impact would snap the hoist cable and cause the suspended load and hook block to plunge to the ground.

Question 10Lifting appliances, forklifts and actual load-control models

How do trolley travel limit switches (*fins de course chariot avant et arrière*) protect the crane jib and mast?

  1. They weigh the load on the trolley wheels at every meter of travel
  2. They trigger automatic deceleration before cutting travel power prior to the trolley striking mechanical end buffer stops Correct answer.
  3. They automatically drop the hook whenever the trolley approaches the jib tip
  4. They lock the trolley in a fixed position whenever rain is detected

Explanation

Appropriate trolley travel limits prevent the intended movement beyond the designed operating range. Actual deceleration, stops and safety behavior depend on the crane and configuration. This concept does not authorize a live limit test, override or assumption that every end condition is protected by one device.

Question 11Lifting appliances, forklifts and actual load-control models

How does an electronic anti-collision system (*système anticollision*) function on construction sites with multiple overlapping tower cranes (*grues en interférence*)?

  1. It continuously tracks real-time 3D positions, trolley radii, and slewing angles via radio telemetry, automatically slowing and stopping conflicting movements before collision zones are breached Correct answer.
  2. It blows an audible siren but leaves all motor controls under full manual operator authority
  3. It shuts off primary electrical power to the entire construction site simultaneously whenever two jibs come within 10 meters
  4. It forces the lower crane to drop its load immediately to avoid collision

Explanation

A suitable configured anti-collision arrangement can use actual position information and defined boundaries to restrict conflicting movements. Sensor errors, changes, communications and unmodeled obstacles can affect protection. It supplements the coordinated actual plan rather than guaranteeing that every possible collision is prevented.

Question 12Lifting appliances, forklifts and actual load-control models

What is the function of an electronic forbidden zone flyover system (*système de gestion des zones d'interdiction de survol*) installed on a tower crane?

  1. Preventing birds from perching on the jib lattice structure
  2. Restricting slewing and trolley movements to prevent the hook and load from entering designated 3D protected airspace over schools, public streets, or railways Correct answer.
  3. Locking the anemometer cups whenever the wind blows from the east
  4. Preventing the operator from listening to commercial music in the cab

Explanation

Configured restricted-zone control can limit relevant movements against the defined envelope. The actual hook, load, swing and obstruction geometry must be considered; a stored boundary is not proof of every current site condition. Maintain competent coordination and do not defeat a protective function for convenience.

Question 13Lifting appliances, forklifts and actual load-control models

A supplied rotation-resistant hoist rope uses opposing lay directions to reduce net torsional tendency. Which listed construction purpose explains that design, without asserting the same rope is required on every tower crane?

  1. They are constructed with opposing lay directions in outer and inner strand layers, balancing torsional torque under load to prevent unguided hook spinning Correct answer.
  2. They are made from flexible Kevlar fibers that never require lubrication
  3. They can be knotted together by the operator if snapped without loss of strength
  4. They stretch by 30% under peak load to cushion dynamic shocks

Explanation

Opposing rope-layer lay can reduce the net torsional tendency in the intended rotation-resistant design. It does not guarantee no hook rotation or mean the same rope is suitable for every crane. Use the actual manufacturer selection, reeving and termination basis.

Question 14Lifting appliances, forklifts and actual load-control models

What is the structural distinction between base ballast (*lest de base*) and counter-jib ballast (*lest de contre-flèche*)?

  1. Base ballast is made of lead while counter-jib ballast is made of water tanks
  2. Base ballast is adjusted during every lift while counter-jib ballast is fixed permanently
  3. Base ballast is placed only on mobile cranes while tower cranes have no base ballast
  4. Base ballast stabilizes the stationary mast against overturning at ground level; counter-jib ballast balances the moments of the rotating jib and load aloft Correct answer.

Explanation

Base ballast consists of heavy precast concrete blocks placed on the cross-chassis (*châssis en croix*) at the ground to prevent overturning of the entire mast structure. Counter-jib ballast consists of concrete blocks placed at the tail of the rotating superstructure to counterbalance the horizontal jib and live loads.

Question 15Lifting appliances, forklifts and actual load-control models

What severe hazard occurs if an operator allows slack rope (*mou de câble*) to develop on the hoist winch drum?

  1. The cable can jump drum grooves, cross-wind, and become crushed under subsequent heavy tension, leading to severe wire deformation and sudden failure Correct answer.
  2. The electric motor immediately reverses polarity and catches fire
  3. The counterweights on the counter-jib slide backward off the crane
  4. The anemometer reading drops to zero

Explanation

Slack can permit poor winding, displacement or crushing when tension returns, creating actual rope and control hazards. The severity depends on the arrangement and conditions, not a guaranteed failure on every occurrence. Stop and use the appropriate competent assessment rather than hide or repeatedly load a damaged condition.

Question 16Lifting appliances, forklifts and actual load-control models

On luffing-jib tower cranes (*grues à tour à flèche relevable*), how is the working radius changed during lifting operations?

  1. By extending hydraulic telescopic cylinder sections inside the horizontal boom
  2. By shifting the counterweights forward and backward along the counter-jib
  3. By rolling a standard distribution trolley along the upper chord of the jib
  4. By luffing the entire inclined lattice jib up or down using a heavy-duty luffing winch and tie cables Correct answer.

Explanation

Luffing-jib cranes (often used in congested urban centers with air-rights constraints) have no trolley. The working radius is varied by changing the angle of inclination of the entire jib, pulling it up toward vertical (minimum radius) or lowering it outward (maximum radius) via the luffing winch.

Question 17Lifting appliances, forklifts and actual load-control models

What is the primary structural function of foundation anchor stools (*pieds de scellement*) embedded in a concrete crane base?

  1. Anchoring the lowest mast section directly into a massive reinforced concrete footing block to transmit dynamic overturning moments, shear loads, and deadweight into the ground Correct answer.
  2. Allowing the crane to slide smoothly on railway tracks during windstorms
  3. Providing spring-loaded shock dampening to prevent crane vibrations from affecting adjacent buildings
  4. Acting as sacrificial electrical fuses to ground lightning strikes safely

Explanation

Stationary tower cranes without ground ballast chassis use foundation anchor stools (*pieds de scellement*). These four high-strength steel legs are precisely cast into a massive reinforced concrete foundation pad, transferring all overturning moments (P x R) and wind forces directly into the earth.

Question 18Lifting appliances, forklifts and actual load-control models

A supplied capacity model has only a 120 tonne-metre moment cap and a separate 6.0 tonne gross cap. At a radius of 30 metres, what maximum load follows under those stated caps, before other real-world conditions?

  1. 4.0 tonnes Correct answer.
  2. 6.0 tonnes
  3. 3.0 tonnes
  4. 2.5 tonnes

Explanation

For the supplied two-limit model, the moment allowance gives 120 divided by 30 = 4 tonnes, below the separate 6 tonne gross cap. This answers that stated comparison only; a real lift still needs the actual chart, deductions, configuration, wind and competent plan.

Question 19Lifting appliances, forklifts and actual load-control models

For a supplied moment-only exercise, divide 160 tonne-metres by a 50 metre radius. What load quantity follows from that stated model, rather than a complete actual crane capacity?

  1. 1.6 tonnes
  2. 4.0 tonnes
  3. 3.2 tonnes Correct answer.
  4. 5.0 tonnes

Explanation

Under the supplied moment-only model, 160 tonne-metres divided by 50 metres gives 3.2 tonnes. This is not a complete capacity chart or safe-lift authorization. Other line, structural, accessory and environmental limits remain outside the simplified calculation.

Question 20Lifting appliances, forklifts and actual load-control models

A tower crane's load chart indicates a rated moment of 100 tonne-meters (t.m) and a maximum gross hoist capacity of 5.0 tonnes. At a radius of 15 meters, what is the maximum allowable load the crane can lift?

  1. 6.67 tonnes
  2. 5.0 tonnes Correct answer.
  3. 3.33 tonnes
  4. 7.5 tonnes

Explanation

The supplied moment ratio is 100 divided by 15, about 6.67 tonnes, but the separate gross cap is 5 tonnes. The more restrictive stated limit gives 5 tonnes before other applicable deductions and conditions. A real complete chart and competent assessment remain necessary.

Question 21Lifting appliances, forklifts and actual load-control models

A tower crane has an allowable gross lifting capacity of 4,000 kg at a radius of 28 meters. The hook block weighs 180 kg, the concrete bucket has a tare weight of 320 kg, and the chain slings weigh 50 kg. What is the maximum net payload of wet concrete that can be loaded into the bucket?

  1. 3,820 kg
  2. 3,450 kg Correct answer.
  3. 3,500 kg
  4. 3,250 kg

Explanation

The supplied deductions total 180 + 320 + 50 = 550 kilograms. From the 4,000 kilogram gross allowance, the net object allowance is 3,450 kilograms under that model. Actual chart interpretation and every other lift condition still require verification.

Question 22Lifting appliances, forklifts and actual load-control models

What does the abbreviation *CMU (Charge Maximale d'Utilisation)* stamped on lifting accessories (slings, shackles, spreader beams) indicate?

  1. The ultimate tensile breaking strength at which the accessory will snap
  2. The deadweight mass of the lifting accessory itself
  3. The maximum mass that the accessory is legally certified to support under normal specified lifting conditions Correct answer.
  4. The proof test load applied in a factory testing bench

Explanation

CMU (Working Load Limit - WLL) is the maximum payload that a lifting accessory (sling, shackle, eyebolt, lifting beam) is authorized to lift in routine service. It incorporates a safety factor (e.g. 4:1 for steel chains, 5:1 for steel cables, 7:1 for synthetic webbing) relative to ultimate breaking strength.

Question 23Lifting appliances, forklifts and actual load-control models

What is the primary function of the spring-loaded safety latch (*linguet de sécurité*) mounted on a crane hook?

  1. Preventing slings, master links, or eyebolts from accidentally jumping out of the hook bowl when the hoist rope goes slack or during transit Correct answer.
  2. Increasing the hook's maximum lifting capacity by 20%
  3. Measuring the exact weight of the suspended load
  4. Preventing the hook from rotating on its axial bearing

Explanation

The latch helps retain appropriately seated loose rigging in the hook throat under its actual design. It is not the primary load-bearing surface or permission for tip loading. The complete hook, rigging configuration, condition and manufacturer criteria remain necessary.

Question 24Lifting appliances, forklifts and actual load-control models

Why is diagonal lifting or dragging loads sideways (*tirage en biais*) strictly prohibited when operating a tower crane?

  1. Because it causes the hoist motor to draw too little electrical current
  2. Because it exerts dangerous lateral forces on the jib and mast, inducing high torsional stresses that can buckle the mast and collapse the crane Correct answer.
  3. Because it makes the concrete set too quickly inside the bucket
  4. Because it causes the anemometer cups to spin backwards

Explanation

Side pulling can introduce lateral forces, uncontrolled release and loading outside the intended tower-crane design. The apparent object mass does not bound the force of dragging or freeing a restrained load. Use the actual approved lifting method; this written recognition authorizes no maneuver.

Question 25Lifting appliances, forklifts and actual load-control models

A symmetrical 2-leg chain sling lifts a precast concrete beam weighing 4.0 tonnes. The angle between the two sling legs at the hook is 60° (each leg is 30° from the vertical). What is the tensile force in each sling leg?

  1. Approximately 2.31 tonnes Correct answer.
  2. Exactly 2.00 tonnes
  3. Exactly 4.00 tonnes
  4. Approximately 3.46 tonnes

Explanation

Under the supplied ideal static equal-leg model, each leg carries 4 divided by (2 × cos 30 degrees), approximately 2.31 tonnes-force equivalent. The answer uses a mass-equivalent force convention; a tonne is not an SI force unit. Actual equipment, dynamics and configuration remain separate.

Question 26Elevator mechanical systems, load paths and hydraulic principles

What is the function of an interlock on an elevator hoistway door?

  1. It controls the speed of the elevator car
  2. It prevents the door from opening unless the car is at the landing Correct answer.
  3. It activates the emergency lighting system
  4. It monitors the weight in the elevator car

Explanation

The intended door-lock arrangement controls unsafe access and relevant movement conditions under the actual elevator design. Authorized unlocking or special modes must follow the manufacturer and governing procedures. A component name alone does not establish complete safe access or permission to enter a hoistway.

Question 27Elevator mechanical systems, load paths and hydraulic principles

What is the purpose of the terminal stopping device on an elevator?

  1. To stop the doors from closing
  2. To prevent the car from traveling past the top or bottom terminal floors Correct answer.
  3. To disconnect power at the end of the day
  4. To alert passengers at the terminal floor

Explanation

Terminal stopping devices (normal and final limits) prevent the elevator car from traveling past the uppermost or lowermost terminal floors. The normal terminal stopping device initiates deceleration, while the final terminal stopping device is a backup that removes power if the car overruns the normal stop.

Question 28Elevator mechanical systems, load paths and hydraulic principles

What is the purpose of the governor rope in a traction elevator system?

  1. It drives the main sheave of the elevator
  2. It connects the governor to the safety device on the car frame Correct answer.
  3. It provides power to the elevator car lights
  4. It opens the hoistway doors at each landing

Explanation

The governor rope connects the governor at the top of the hoistway to the safety device mounted on the car frame. When the governor detects an overspeed condition, it grips the governor rope, which in turn activates the safety device to clamp the guide rails and stop the car.

Question 29Elevator mechanical systems, load paths and hydraulic principles

What is the purpose of a car safety device (safeties) on a traction elevator?

  1. To prevent the doors from opening between floors
  2. To stop the car by clamping the guide rails in case of overspeed or free fall Correct answer.
  3. To monitor the weight capacity of the car
  4. To provide emergency lighting during a power failure

Explanation

The specified car safety acts through its designed guide-rail engagement under the relevant triggering condition. It is distinct from the machine brake, governor sensing and normal leveling functions. Actual type, direction, speed and test requirements depend on the equipment and applicable code, not a universal release or test recipe.

Question 30Elevator mechanical systems, load paths and hydraulic principles

What is the purpose of compensation chains or ropes on high-rise traction elevators?

  1. To provide additional lifting capacity
  2. To equalize the weight of the hoist ropes on both sides of the sheave as the car travels Correct answer.
  3. To serve as a backup in case the main ropes break
  4. To reduce noise during elevator operation

Explanation

Compensation chains or ropes are attached to the bottom of the car and counterweight to equalize the weight of the hoist ropes on both sides of the drive sheave. In tall buildings, the significant weight of long hoist ropes would create an imbalance without compensation, affecting motor performance.

Question 31Elevator mechanical systems, load paths and hydraulic principles

What is the primary purpose of a rope gripper device on a traction elevator?

  1. To grip passengers entering the car
  2. To grip the hoist ropes and stop the car if the machine brake fails or rope slippage is detected Correct answer.
  3. To tighten loose ropes during maintenance
  4. To attach the ropes to the counterweight

Explanation

A suitable emergency braking arrangement can act on the suspension under the actual triggering and equipment design. It is distinct from normal drive control and must be selected, installed and verified as a complete protective function. The name does not guarantee detection of every brake or traction failure.

Question 32Elevator mechanical systems, load paths and hydraulic principles

What is the primary purpose of the machine brake on a traction elevator?

  1. To slow down the car during normal operation
  2. To hold the car stationary when the motor is not running and to stop the car in an emergency Correct answer.
  3. To increase the speed of the car
  4. To prevent the doors from opening

Explanation

The machine brake provides the designed holding and stopping function under the actual elevator architecture. It is not interchangeable with every car safety, governor or emergency brake. Actual drive sequencing, load, wear and protective verification matter; no universal brake adjustment or live test follows from the label.

Question 33Elevator mechanical systems, load paths and hydraulic principles

In a hydraulic elevator system, what component creates the pressure to raise the elevator car?

  1. A counterweight system
  2. A positive displacement pump driven by an electric motor Correct answer.
  3. A compressed air reservoir
  4. A spring-loaded mechanism

Explanation

A positive displacement pump, driven by an electric motor, creates the hydraulic pressure needed to push oil into the cylinder, which extends the plunger and raises the car. When descending, the pump is off and a control valve allows oil to flow back to the reservoir under gravity.

Question 34Elevator mechanical systems, load paths and hydraulic principles

What component in a hydraulic elevator system controls the rate of descent of the car?

  1. The electric motor
  2. The control valve (down valve) Correct answer.
  3. The governor
  4. The counterweight

Explanation

The control valve (also called the down valve or lowering valve) regulates the flow of oil from the cylinder back to the reservoir, controlling the rate of descent. By varying the valve opening, the system can achieve smooth deceleration and precise leveling during the down run.

Question 35Elevator mechanical systems, load paths and hydraulic principles

What is the primary difference between a direct-acting and a roped hydraulic elevator?

  1. Direct-acting uses cables while roped hydraulic uses a piston
  2. In a direct-acting system, the plunger pushes the car directly; in a roped system, the plunger pulls ropes attached to the car Correct answer.
  3. Direct-acting systems are faster than roped hydraulic systems
  4. There is no functional difference

Explanation

In the defined direct arrangement, the plunger acts directly on the car support; a roped arrangement transmits motion through its designed sheave and suspension geometry. Actual speed and force ratios depend on that geometry. The distinction is not permission to substitute parts or calculate every system from one assumed ratio.

Question 36Elevator controls, maintenance evidence and authorized scope

What is the purpose of Phase I emergency recall operation (firefighters' service) on an elevator?

  1. To allow firefighters to manually operate the elevator during a fire emergency
  2. To automatically recall the elevator to a designated floor upon activation of a fire alarm or smoke detector Correct answer.
  3. To shut down all elevators permanently during a fire
  4. To activate the sprinkler system in the hoistway

Explanation

The described Phase I function recalls the car under the actual fire-service design, which can include designated or alternate landing behavior. It is distinct from ordinary calls and from the firefighter’s subsequent controlled operation. Do not improvise a live test or assume one landing is always safe.

Question 37Elevator controls, maintenance evidence and authorized scope

In Phase II firefighters' service operation, who has control of the elevator?

  1. The building manager
  2. The fire department personnel using a special key Correct answer.
  3. The elevator automatically runs to each floor
  4. The elevator maintenance company via remote control

Explanation

The stated Phase II mode provides the designed firefighter-controlled operation using the actual authorized controls and procedures. It is not a general passenger or maintenance mode and does not make every route safe during a fire. Written recognition does not authorize emergency elevator use.

Question 38Elevator controls, maintenance evidence and authorized scope

What is the function of door reopening devices (safety edges or photo eyes) on elevator doors?

  1. To keep doors open permanently
  2. To detect obstructions in the door path and reverse the closing doors to prevent injury Correct answer.
  3. To lock doors in the closed position
  4. To increase door closing speed

Explanation

The intended reopening device detects a relevant obstruction and commands the specified door response. Coverage, response, actual door force and other protective functions still matter. It does not guarantee prevention of every injury or replace proper maintenance and the complete approved door system.

Question 39Elevator controls, maintenance evidence and authorized scope

What is the function of a load-weighing device in an elevator system?

  1. It controls the lighting level inside the car
  2. It measures the load in the car to optimize motor torque and prevent overloading Correct answer.
  3. It tracks the number of passengers for building security
  4. It adjusts the door opening speed

Explanation

Load-weighing devices measure the weight inside the elevator car. They serve multiple functions: preventing the car from operating when overloaded, optimizing motor torque for smooth starts, and enabling features like bypass of hall calls when the car is near capacity.

Question 40Elevator controls, maintenance evidence and authorized scope

What type of elevator drive system uses a variable frequency drive (VFD) to control motor speed?

  1. Single-speed AC motor system
  2. Two-speed AC motor system
  3. AC variable voltage variable frequency (VVVF) system Correct answer.
  4. Ward-Leonard DC motor system

Explanation

An AC VVVF (variable voltage variable frequency) system uses a VFD to control the speed of the AC motor by varying both the voltage and frequency of the power supplied. This provides smooth acceleration and deceleration, energy efficiency, and precise floor leveling - it is the most common modern drive type.

Question 41Elevator controls, maintenance evidence and authorized scope

What is the purpose of a leveling device on an elevator?

  1. To level the machine room floor
  2. To ensure the car floor aligns precisely with the landing floor at each stop Correct answer.
  3. To balance the counterweight
  4. To adjust the governor speed

Explanation

A leveling device automatically adjusts the position of the elevator car so that its floor is precisely aligned with the landing floor. This prevents tripping hazards and ensures smooth entry and exit. ASME A17.1 specifies maximum permitted leveling tolerances, typically within 1/2 inch.

Question 42Elevator controls, maintenance evidence and authorized scope

What is the function of the selector in an elevator control system?

  1. It selects which elevator in a group responds to a call
  2. It tracks the position of the car in the hoistway and determines stopping points Correct answer.
  3. It selects the type of music played in the car
  4. It chooses the appropriate wire rope for the installation

Explanation

The selector is a device that continuously tracks the position of the elevator car within the hoistway. It provides position information to the controller so the system knows when to initiate slowdown and stopping at the correct floor. Modern systems use encoders and magnetic sensors for this function.

Question 43Elevator controls, maintenance evidence and authorized scope

What is the function of a regenerative drive on a traction elevator?

  1. It provides backup battery power during outages
  2. It captures energy during descent and feeds it back to the building's electrical system Correct answer.
  3. It regenerates worn wire ropes
  4. It recharges the emergency battery for car lighting

Explanation

A regenerative drive can return braking energy to the designed electrical path when the actual force balance and direction permit it. A loaded descent or sufficiently light ascent can generate under suitable conditions; descent alone does not guarantee regeneration. The drive can retain hazardous electrical energy and written recognition authorizes no access.

Question 44Elevator controls, maintenance evidence and authorized scope

In a group elevator system, what does 'dispatching' refer to?

  1. Sending a mechanic to perform repairs
  2. The logic that determines which elevator in a group responds to a hall call Correct answer.
  3. Shipping elevator parts to a job site
  4. The process of installing a new elevator

Explanation

Dispatching in a group elevator system refers to the control logic that determines which elevator car should respond to a particular hall call. Modern dispatching algorithms consider factors like car position, direction of travel, current load, and wait times to optimize passenger service and minimize wait times.

Question 45Elevator controls, maintenance evidence and authorized scope

What is the function of the traveling cable in an elevator system?

  1. It supports the weight of the elevator car
  2. It carries electrical power, communication signals, and data between the car and the controller Correct answer.
  3. It provides ventilation to the hoistway
  4. It serves as a backup hoist rope

Explanation

The traveling cable is a flexible cable that connects the elevator car to the stationary controller in the machine room. It carries power for car lights, door operator, and fans, as well as communication signals, position data, and intercom lines. It must withstand continuous flexing as the car moves.

Question 46Maintenance diagnosis, condition evidence and controlled restoration

Over a six-month observation period (total operating time T = 4,320 hours), an automated coil slitting line experienced 12 unscheduled breakdown stoppages. What is the Mean Time Between Failures (MTBF) and the corresponding failure rate (λ)?

  1. MTBF = 360 hours; λ ≈ 0.00278 failures/hour (2.78 × 10⁻³) Correct answer.
  2. MTBF = 12 hours; λ = 0.083 failures/hour
  3. MTBF = 51,840 hours; λ ≈ 0.000019 failures/hour
  4. MTBF = 360 days; λ = 2.78 failures/hour

Explanation

Under standard reliability definitions (AFNOR NF EN 13306): MTBF = Total Operating Time / Number of Failures = 4,320 hours / 12 = 360 hours. The failure rate λ is the reciprocal of MTBF: λ = 1 / MTBF = 1 / 360 ≈ 0.00278 failures per operating hour.

Question 47Maintenance diagnosis, condition evidence and controlled restoration

During the same six-month period on the coil slitting line, the cumulative downtime spent on active corrective repairs across all 12 breakdowns totaled 42 hours. What is the Mean Time To Repair (MTTR), which serves as the key indicator of equipment maintainability?

  1. MTTR = 0.29 hours
  2. MTTR = 3.5 hours Correct answer.
  3. MTTR = 42.0 hours
  4. MTTR = 7.0 hours

Explanation

Under AFNOR NF EN 13306: MTTR = Total Corrective Maintenance Time / Total Number of Corrective Actions = 42 hours / 12 repairs = 3.5 hours per breakdown. MTTR directly measures the maintainability of the installation and efficiency of technician troubleshooting.

Question 48Maintenance diagnosis, condition evidence and controlled restoration

In the supplied simplified availability model A=MTBF/(MTBF+MTTR), use450hours and4.5hours. What value results, excluding other logistical or scheduled delays?

  1. Ao = 90.00%
  2. Ao = 95.50%
  3. Ao = 99.01% Correct answer.
  4. Ao = 99.90%

Explanation

Operational availability is calculated using the standard reliability formula Ao = MTBF / (MTBF + MTTR) = 450 / (450 + 4.5) = 450 / 454.5 ≈ 0.9901 (99.01%). This means the rolling stand is operational and capable of production 99.01% of its scheduled operating time.

Question 49Maintenance diagnosis, condition evidence and controlled restoration

A maintenance progress group performs an AMDEC Machine (FMEA) on an automated robotic welding cell. For the failure mode 'welder positioner drive belt snapped', the team assigns: Gravity G = 4 (severe production stoppage > 4 h), Occurrence F = 3 (frequency ~once every 2 months), Non-Detection D = 3 (detected only after bad parts are produced). The plant policy mandates technical corrective action when Criticality C ≥ 30. What is the calculated Criticality Index C and what conclusion is drawn?

  1. C = G × F × D = 4 × 3 × 3 = 36; because C exceeds the threshold of 30, the progress group must design and implement a technical improvement (such as installing a non-contact inductive speed monitoring sensor to drop D to 1) Correct answer.
  2. C = G + F + D = 10; because 10 < 30, no action is required and the failure is accepted
  3. C = 4 × 3 = 12; Non-detection is never factored into AMDEC calculations
  4. C = 433; the plant must be immediately decommissioned

Explanation

For the supplied scoring model, 4×3×3=36, which exceeds its stated internal threshold30. The result triggers the specified review, not proof that a particular sensor makes the risk acceptable. Confirm appropriate safety controls and validate any change through competent engineering assessment.

Question 50Maintenance diagnosis, condition evidence and controlled restoration

Operators on an automated sheet bending press occasionally insert asymmetrical stamped blanks backward into the die, causing punch collisions and tooling damage. The maintenance technician proposes a Poka-Yoke (système anti-erreur / détrompeur) technical improvement. Which solution exemplifies a true Poka-Yoke?

  1. Placing a warning sign on the press guard instructing operators to pay closer attention
  2. Adding an asymmetrical locating guide pin (détrompeur mécanique) or optical profile sensor in the die nesting plate that physically prevents backward insertion or inhibits press cycle start if the blank orientation is incorrect Correct answer.
  3. Increasing the press speed by 50% so operators have less time to think
  4. Imposing financial fines on operators who misfeed parts

Explanation

A Poka-Yoke (mistake-proofing) is a mechanism that either makes it physically impossible to make a mistake (mechanical keying/asymmetric pin) or detects an error immediately and shuts down the operation before damage occurs (profile sensor interlock). Signs, warnings, and administrative penalties rely on human vigilance and do not constitute Poka-Yoke.