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Questions and Answers
What is one major disadvantage of pneumatic motors compared to electric motors?
What is one major disadvantage of pneumatic motors compared to electric motors?
Why are pneumatic motors suitable for use in steamy atmospheres?
Why are pneumatic motors suitable for use in steamy atmospheres?
What can occur when pneumatic motors are idle?
What can occur when pneumatic motors are idle?
What is a potential hazard of small leaks in pneumatic systems, especially in dusty environments?
What is a potential hazard of small leaks in pneumatic systems, especially in dusty environments?
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What precaution should be taken when inspecting power supply wires?
What precaution should be taken when inspecting power supply wires?
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What is the primary reason pneumatic motors require less protective measures than electrical equipment in harsh environments?
What is the primary reason pneumatic motors require less protective measures than electrical equipment in harsh environments?
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What is a consequence of not taking steps to remove moisture from pneumatic systems?
What is a consequence of not taking steps to remove moisture from pneumatic systems?
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What is a major cause of burns on power supply wires and collector mechanisms?
What is a major cause of burns on power supply wires and collector mechanisms?
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What is a primary advantage of the tracked cable system over the taut wire system?
What is a primary advantage of the tracked cable system over the taut wire system?
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What is a typical feature of tracked festoon systems?
What is a typical feature of tracked festoon systems?
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Which of the following is likely a requirement for long track installations of tracked festoon systems?
Which of the following is likely a requirement for long track installations of tracked festoon systems?
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In a lifting appliance with two festoon tracks, what does one track typically provide?
In a lifting appliance with two festoon tracks, what does one track typically provide?
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What could be a limiting factor for the operation of a festoon system?
What could be a limiting factor for the operation of a festoon system?
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What track shape do most tracked cable systems incorporate?
What track shape do most tracked cable systems incorporate?
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What is an expected outcome of employing a mobile pendant push button box with a festoon cable?
What is an expected outcome of employing a mobile pendant push button box with a festoon cable?
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What is a characteristic of typical components of a tracked festoon cable supply?
What is a characteristic of typical components of a tracked festoon cable supply?
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What is the primary function of a hook operated limit switch?
What is the primary function of a hook operated limit switch?
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Which statement is true about the automatic reset of a hook operated limit switch?
Which statement is true about the automatic reset of a hook operated limit switch?
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Where is the rotary limit switch unit for hoisting typically found?
Where is the rotary limit switch unit for hoisting typically found?
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What is the purpose of the ultimate limit switch in a hoist?
What is the purpose of the ultimate limit switch in a hoist?
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How are most electric power hoists' limit switches arranged in the control circuit?
How are most electric power hoists' limit switches arranged in the control circuit?
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What occurs in the control circuit when one limit switch is ‘open’?
What occurs in the control circuit when one limit switch is ‘open’?
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Which limit switch is used when the control limit switch fails?
Which limit switch is used when the control limit switch fails?
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What is the main advantage of using hook operated limit switches in hoisting operations?
What is the main advantage of using hook operated limit switches in hoisting operations?
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What sound indicates that a bearing is in good condition?
What sound indicates that a bearing is in good condition?
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What is the primary function of the cupped washers in the lever arm mechanism?
What is the primary function of the cupped washers in the lever arm mechanism?
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Which of these is NOT a benefit of using VFD inverters in industrial applications?
Which of these is NOT a benefit of using VFD inverters in industrial applications?
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At what percentage of the Working Load Limit (WLL) is the load limiter set?
At what percentage of the Working Load Limit (WLL) is the load limiter set?
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What is the primary function of a listening rod when checking equipment?
What is the primary function of a listening rod when checking equipment?
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What action does the strain gauge perform when it reaches the preset limit under load?
What action does the strain gauge perform when it reaches the preset limit under load?
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What operation mode allows for changing the speed and running direction of a motor?
What operation mode allows for changing the speed and running direction of a motor?
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According to BS EN 14492-2, what must hoist brakes be designed to do?
According to BS EN 14492-2, what must hoist brakes be designed to do?
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What are pulses of positive and negative direct current used for in a VFD inverter?
What are pulses of positive and negative direct current used for in a VFD inverter?
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Which scenario requires the hoist brakes to engage automatically?
Which scenario requires the hoist brakes to engage automatically?
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What happens if two phases of the power supply to a three-phase motor are interrupted?
What happens if two phases of the power supply to a three-phase motor are interrupted?
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What should be checked along with motor bearings to ensure proper operation?
What should be checked along with motor bearings to ensure proper operation?
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How does using a VFD inverter contribute to operational efficiency?
How does using a VFD inverter contribute to operational efficiency?
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Which condition does NOT trigger the engagement of hoist brakes?
Which condition does NOT trigger the engagement of hoist brakes?
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What is PWM an acronym for in the context of VFDs?
What is PWM an acronym for in the context of VFDs?
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What component connects the rope to the load limiter in the rope-operated load limiter?
What component connects the rope to the load limiter in the rope-operated load limiter?
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Study Notes
Festoon Systems Overview
- Tracked cable systems enhance taut wire systems, accommodating greater loads and higher speeds.
- Typically feature an inverted ‘U’ or ‘C’ shaped track for cable support trolleys on inner ledges.
- Offer a range of profile sections tailored to various loading conditions, from light to heavy duty.
- Safe design ensures insulation and prevents energy loss or voltage drop during current transfer.
- For long installations, larger cables may be required to limit voltage drop, necessitating stronger tracks.
Components and Considerations
- Festoon systems may include two tracks: one for power supply and another for a mobile pendant control box.
- Pendant control boxes are suspended from the festoon cable to facilitate operator control.
- Systems must address potential hoist travel loss due to trolley bunching, particularly in long applications.
Pneumatic Motors
- Pneumatic motors are lighter and typically smaller than electric motors for similar capacities.
- Designed to withstand high heat and moisture, ideal for environments like laundries and paper mills.
- Self-purging feature minimizes internal contamination, making them robust for harsh conditions.
- Compressed air is less efficient than electricity, requiring moisture removal to prevent corrosion.
Safety and Inspection Protocols
- Implement Lock Out-Tag Out (LOTO) procedures for safety during inspections.
- Check copper wires for burn damage due to arcing; replacements are warranted if burns exceed 25% of diameter.
- Monitor collector shoes and roller collectors for burns and wear, primarily caused by vibrations or faulty mechanisms.
Limit Switches
- Hook operated limit switches stop hoist movement at adjustable lever positions; can have automatic or manual reset.
- Rotary limit switches contain contacts for essential operations and are located in the hoist's gearbox connection box.
- Ultimate limit switches are critical for preventing damage by halting motor operation if other switches fail.
- Control limit switches in electric hoists are arranged in parallel, allowing motion even if one switch is open.
Load Limiting and Braking Systems
- Load limiters detect excessive loads and cease motor power to prevent damage; calibrated to 110% of the Working Load Limit (WLL).
- BS EN 14492-2 outlines requirements for hoist braking systems to ensure safety during movements.
- Brakes must automatically engage under specific conditions, like loss of control device position or power interruption.
Variable Frequency Drives (VFDs)
- VFDs control speed and direction of 3-phase motors through changes in supply frequency.
- Essential for applications requiring precise speed control, particularly in overhead cranes.
- Offer benefits such as improved reliability, reduced downtime, lower energy consumption, and minimized maintenance costs.
- VFD operation often utilizes Pulse Width Modulation (PWM) to simulate an AC motor's sine wave through controlled pulses.
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Description
Test your knowledge on overhead travelling cranes with a focus on festoon trolleys and cables. This quiz covers the technical aspects of different cable systems and their applications. Perfect for those studying cranes and lifting systems.