ESCONDIDO FIRE DEPT TRAINING MANUAL Section Truck Module Page 1 of 8 Ropes - Knots Revised

Transcription

1 Truck Module Page 1 of 8 SERVICE KNOTS Common Knot Tying Terms Working End- the working end of a rope is the part used in forming a knot. (also known as the loose end or bitter end) Running End- the running end of a rope is the part that is to be used for work such as hoisting, pulling or belaying. Standing Part- the standing part of a rope is between the working end and the running end. Bight- a bend or "U" turn in the rope Knot- a knot is a rope or webbing that is intertwined Bend- a bend is two rope or webbing ends connected together Loop- any turn in the rope that crosses over itself, can be an overhand or underhand loop Bight- a bight is formed by simply bending the rope back on itself while keeping the sides parallel Round Turn- a round turn is made by continuing to cross one side of a loop all the way around to form a circle with the ends of the rope parallel as in a bight Hitch- a hitch is a rope or webbing around an object (if the object is removed the hitch will fall apart).

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3 Truck Module Page 3 of 8 Several factors are important concerning service knots. Knots should be easily tied, un-tied, and identified. There should be minimal or no strength loss to the rope. Remember to always use the right rope system for the job. Identify the weakest link in the system to determine the operational load limit. Never allow anyone to stand in line or within a 45 degree on either side of a rope under tension. If the system fails, the recoil force could cause serious injury or death. Working End Standing Part Running End **Always clean-up your knot to improve strength Zone Fire Departments use approved fire service knots designed for rescuer safety. Rescuers should understand the importance of knot strength and how it impacts the rope system. How the knot is formed determines the knot strength. Knots can retain from 43 to 100% of the ropes overall strength. For example, to join two ropes together a rescuer may tie a Square Knot (43%) or Figure 8 Bend (80%). Based on the knot strength, the Figure 8 Bend would be the best knot to maintain the overall strength of a rope. In fact, the family of Figure 8 knots allows retention of percent of the rope s rated strength. Rescuers should utilize a Figure 8 knots to support life loads. Finally, all knots must be tied with enough tail to tie a safety on the end. Some knots require a safety, while others do not. It is always good practice to tie safety knots, even when they are not absolutely necessary. A safety in nylon rope is an overhand knot tied around the rope, or two half hitches. Remember, excessively long tails may interfere with other rope rescue components.

4 Truck Module Page 4 of 8 Figure 8 Stopper A Stopper knot keeps the end of the line from running through an object Starting knot for Figure 8 Bend and Figure 8 Follow-Through Figure 8 on a Bight Forming a bight at the end of a line Forming a bight at any part of a line Commonly used to clip into Carabiner coming off of an anchor sling Note: The size of the bight varies on the application. Anchor attachments should be small. Pelvic and chest harness attachments would be larger. Double Figure 8 on a Bight Forming a bight at the end of a line Commonly used to clip into Carabiner coming off of an anchor sling Note: The size of the bight varies on the application. This knot is preferred for anchor attachments.

5 Truck Module Page 5 of 8 Figure 8 Bend Joining two lines together that are approximately equal diameter Note: Start with a Stopper Knot. End of second rope weaves through the stopper. The ends of the ropes finish on opposite sides of the knot. Figure 8 Follow Through Use To secure a line around or through a trussed anchor Note: Start with a Stopper Knot. The working end goes around the anchor and weaves back through the stopper. The ends of the rope finish on the same side of the knot. Inline Eight Provides an in-line attachment Situations where you need to tension the main line Used in place of Gibbs or Prusik Retains 85% - 90% tensile strength Note: Starting with a bight in the rope, wrap the bight around the mainline in a Figure 8 fashion. The bight should exit next to the main line.

6 Truck Module Page 6 of 8 Square Knot Secure two rope/webbing ends Tie bandages on victims Situations where ease of removal is important Disadvantages Safety knots must be tied because slippage can occur Strength loss is excessive, retains only 43% - 47% tensile strength Bowline Tying ropes used as lifelines Securing lines to fixed anchors Advantage Does not slip or jam Disadvantage Line will retain 50% tensile strength Should not be used on human loads Butterfly Knot Provides an in-line attachment Situations where you need to tension a line Used in place of a Gibbs, Prusik or In-line 8

7 Truck Module Page 7 of 8 Overhand Bend (Also known as a Water Knot) Join the ends of nylon webbing together or to form a loop or sling Use when tying off a Swami sit harness Disadvantages Retains 60% - 70% tensile strength Becket Bend Join two unequal items together Largest rope forms the bight Clove Hitch Up or Down - Depending on Direction of Pull) Use Fastening a rope around a fixed object Disadvantage This knot has a tendency to slip so it requires an overhand safety knot Retains 60% - 65% tensile strength UP DOWN

8 Truck Module Page 8 of 8 Double Overhand Bend Joining together two lines of equal diameter Forming temporary or permanent loops (i.e., Prusik Loop) Retains 85% tensile strength Three Wrap Prusik Hauling or Braking cam in rope systems Securing rescuer or victim to a sing harness and/or a fixed line Tandem Prusik increase overall strength Advantage Will not come undone under stress Disadvantage Wrap will slip at approximately 800 to 1000 lbs. of tension Create a Nylon-on-Nylon situation