SRT Mechanical Advantage & Z-Drag 3 — Questions and Answers
Question 1: A 5:1 mechanical advantage system requires how many rope segments supporting the load compared to a 3:1 system?
- The same number
- Two more segments (Correct answer)
- One fewer segment
- Twice as many segments
Correct answer: Two more segments
A 5:1 has five rope segments supporting the load versus three in a 3:1, requiring additional pulleys and a longer rope run.
Question 2: What is the theoretical mechanical advantage of a piggyback (3:1 added to a 3:1) compound system?
- 6:1
- 9:1 (Correct answer)
- 12:1
- 5:1
Correct answer: 9:1
A 3:1 pulling on another 3:1 multiplies the advantages: 3 × 3 = 9:1 theoretical mechanical advantage.
Question 3: During a Z-drag operation in swiftwater, which team member's role is to call 'take!' and 'reset!' to coordinate the haul cycle?
- The swimmer in the water
- The team leader or haul team captain (Correct answer)
- The person tending the progress-capture device
- The anchor attendant
Correct answer: The team leader or haul team captain
The team leader or haul captain gives verbal commands to synchronize hauling and PCD management so the load never slips.
Question 4: When a Z-drag rope passes over a sharp rock edge, what is the recommended mitigation to reduce rope damage and friction?
- Use a thicker rope
- Apply a rope pad or edge protector (Correct answer)
- Increase the mechanical advantage
- Shorten the haul distance
Correct answer: Apply a rope pad or edge protector
Edge protectors or rope pads shield the rope from abrasion and reduce friction, preserving rope integrity and system efficiency.
Question 5: If a prussik used as a PCD fails to hold the haul line, which of the following is the MOST likely cause?
- The prussik cord is too long
- The prussik cord diameter is too large relative to the haul line
- The prussik cord diameter is too small relative to the haul line (Correct answer)
- The prussik is tied with too many wraps
Correct answer: The prussik cord diameter is too small relative to the haul line
A prussik cord that is too thin relative to the haul line will not generate enough friction to grip effectively under load.
Question 6: In a swiftwater rescue Z-drag, what is the safest method to attach the traveling pulley to a victim's boat pin or foot entrapment harness?
- Overhand knot tied directly to the harness
- Large locking carabiner clipped to a properly rigged rescue loop (Correct answer)
- Wrap the rope three times around the anchor point
- Non-locking carabiner for quick release
Correct answer: Large locking carabiner clipped to a properly rigged rescue loop
A locking carabiner on a properly configured rescue loop ensures the connection will not unclip under load or vibration.
Question 7: Which statement best describes the difference between a simple and a compound mechanical advantage system?
- Simple systems use pulleys; compound systems use only rope wraps
- Simple systems have all movable pulleys; compound systems have all fixed pulleys
- A simple system is a single arrangement of pulleys; a compound system uses one simple system to haul another (Correct answer)
- Compound systems always provide less mechanical advantage than simple systems
Correct answer: A simple system is a single arrangement of pulleys; a compound system uses one simple system to haul another
A compound system multiplies mechanical advantage by using one simple haul system to drive another, yielding higher ratios.
SRT Mechanical Advantage & Z-Drag 3
A 5:1 mechanical advantage system requires how many rope segments supporting the load compared to a 3:1 system?