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 LOWERING SYSTEMS


 In technical rescue the objective is to extricate a possibly injured subject from a precarious situation to a safe location for further evacuation. If possible when evacuating from a vertical rock face or high mountain situation, a lowering system which uses gravity to pull the rescue load down is preferred. A lowering system requires less work from the rescuers than a raising system and therefore can normally be achieved with less total rescuers. Of course an evacuation path must exist from the bottom of the evacuation via some sort of transportation (i.e. litter, ambulance, or SAR truck) once the lowering systems have been completed.  

DEFINITIONS

Braking Device is any device intended to apply friction to rope for the purpose of slowing or stopping the progress of the rope travel. i.e. Figure 8's, Rescue 8's, Brake bars, etc.  

Lock-Off is the process of securing a brake system in such a way that rope travel is not allowed in any direction. Also an operator is not required to maintain pressure or tension while the system is Locked-off.  

Braking Hand is the operator's hand that must never leave a rope during a lowering operation. This is similar to the braking hand used in belays. The intent is that if the operator has contact with the rope when a sudden surge or load change occurs, he will able to best respond to the load change if the rope is guaranteed to be in his hand.  

Feeling Hand is the operator's hand that is used to monitor the tension of the main lowering line. Lowering systems are designed to work with the weight of the load. If slack is formed in the main line this may indicate that the rescue load has become momentarily hung up on a ledge or is at the bottom. The operator strives to maintain no slack in the line unless slack is required for some specific purpose.  

GENERAL LOWERING INFORMATION  

The lowering systems used by SAR, work in a similar fashion to the rappelling systems which are based on friction created by bending rope about a device with a tight turning radius. In this case the braking device is held stationary and the rope (attached to the load) is allowed to move.  As is the case with all rescue operations, redundant belays are required in addition to the lowering system. A lowering station can be comprised of one or more rescuers depending on the load and the amount of friction being created by the braking device. Lowering systems are designed to require a minimum amount of force (strength) to operate as the load is held by the system brake device. The lowering system operators control the speed of descent and have the ability to "lock off" or stop and secure the system. Rope management at the scene is important to prevent rope twists and entanglement from interrupting the flow of the operation. The lowering station will normally operate under the command of a field manager or an operations leader. Extreme care must be exercised to watch fingers and loose equipment to prevent entrapment in the lowering system. If assigned to create and operate a lowering station, advise the leader of its completion after construction is finished and stand by the system in a ready state unless advised otherwise.  

Dynamic edge protections, such as edge rollers, should be utilized when available to protect the rope from abrasion during a lowering operation. If dynamic edge protection is not available, low resistance protection should be used to protect the rope from sharp or abrasive rocks. The rope is expected to take some abrasion against the rock during an operation.  

Simple commands are used to control the operation of the lowering system. They are:  Lower away, Faster, Slower, Stop, Lock-off, Convert to Raising, and Break down. Normal systems protocol allows anyone to stop a lowering system, but allows only the operation's leader to restart lowering.  

Each brake system has its own requirements which are explicitly specified below. Additional gear to convert to a raising system, and prussiks should be available in the event a problem arises with the lowering system.  

FIGURE OF EIGHT LOWERING SYSTEM  

The team standard lowering brake is the "rescue 8" device which is normally used for rappelling. The rescue 8 is larger than a normal figure 8 rappel device, has "lock-off ears" to facilitate easier and more stable lock-offs, and has a extra attachment slot for connection of an extra person or for use a as a stitch plate. The "rescue 8" device is shown in figure-1. The rescue 8 may be used with 6 to 13 mm rope with loads up to 1000 lbs. Speed control is managed in the same manner as is used for rappelling.  

To slow or stop the load, tension is applied to the free or brake side of the rope and the rope is pulled at a right angle to the main axis of the figure 8 as is shown in figure-2. Pulling the rope at a right angle to the major axis of the figure 8 device creates the tightest angle and therefore applies the most amount of friction. When lowering rescue loads, especially large loads above 300 lbs, a slow pace should be used. Stops should be applied gradually if possible to dissipate the energy over time rather than in heat on a quick stop. Quick stops or jolts always stress a system more than continuous loads cause an increased amount of heat and may lead to a system failure. Whenever actively operating a lowering system, the operator should be wearing leather gloves to protect the hands from injury. (In addition to the possibility of rope burns, the rope could contains thorns or cactus spikes which would become embedded in the hands if leather gloves are not worn.  

Normally a lowering station will consist of 3 to 4 people based on the number of people available. One person should be delegated to be responsible for rope management. Figure 8 lowering systems have a characteristic inherent disadvantage which is caused by the "spinning" of the rope as it passes through the brake. This spinning causes tension between the rope fibers and the sheath which can make the rope hard to handle after 200 to 300 foot lowering operations. The effects of the spinning can be minimized by loosely flaking the rope into a large pile prior to feeding it through the brake. If it is necessary to use several rope lengths, as in one long lowering system, tie the next rope into the system only when nearing the completion of the lowering of the previous length of rope. By connecting the lines just prior to their use, the twist that was accumulated in the first line can be completely dissipated prior to attaching the next line. Otherwise, if the lines were connected earlier, the second line would receive twist from the first line. As a rule never attempt to pass more than 400 ft of continuous rope through a figure 8 lowering station.  

Rescue 8 lowering systems provides the easiest and most secure lock-off capability. Lock-offs are requested to place the lowering system in a locked state where the secured brake is preventing any further lowering of the system. To lock a rescue 8 one first draws the free end across the top of the figure eight and across the load side of the rope as is shown in figure-3. This places friction between the two sides of the rope.  

To prevent the lock from disengaging easily the rope is wrapped around the eight and a second wrap is placed as is shown in figure-4. (This would complete the lock-off for a normal figure 8.)  To complete the lock-off when "Ears" are available on the brake, a bight of the rope is inserted into the eight, and pulled tightly against the ears as is shown in figure-5. If the lowering system is to remain locked for an extended period of time, the lowering line (main) could be secured with a prussik as is shown in figure-6, (Note use of the mariner's knot) or the main may be knotted and secured as is shown in figure-7. Knotting the rope or placing a prussik on the main line should only be used when the lock-off time is not expected to be short. However, knotting the rope or a prussik back-up is required if the operator must leave the station for some reason. (Although not preferable, if a problem arises and the personnel is limited, the lowering system operator may be required to secure the lowering station and then move to assist in some other aspect of the operation.

As has been mentioned often, the lowering system requires a valid sturdy anchor. Separate anchors must be used for the different systems in use (i.e. Belay and Lowering would be separate anchors).  

PASSING KNOTS WITH A FIGURE OF EIGHT LOWERING SYSTEM  

Knot passing is required when a single length of rope will not suffice the necessary lowering length requirement and additional lowering stations are not possible or are not desired. Winter evacuation down long low angle slopes often create demands to lower a litter several thousand feet. Obviously a rescue team can only carry a limited amount of rope into the field. Team 1 uses 200', 300', 400', 165' (climbing line), and 600' rope spools for operations. The operations leader will make a decision based on available equipment as to the length of the lowering station and the position of the lowering stations if more than one station is required to do the required job.  

The trade-off between extending the length of a lowering station is not always clear. The added rope length increases the amount of rope friction if the station is not a pure overhand, complicates the rope twist problem if using a figure 8 brake device, and extends the distance between the rescue personnel at the load and the team at the lowering station. More lowering stations require additional hardware, additional sites for the stations to be assembled, additional personnel to man each station, and coordination between the various stations. Since 200 ft sections are the typical rope length used in the backcountry, the following guidelines would apply. If the evacuation is 400 ft or less with no change of direction required, then it would be best to use extended ropes tied together. (Remember in addition to lengthening the main line a belay will also be doubled.)  If the evacuation is greater than 400 ft and can be completed easily in 3 or less stations than multiple stations should be used on single length ropes. In longer evacuations, multiple stations using extended (or knotted) lines will be required. Passing knots will be required whenever shorter sections of rope must be joined to form one usable length of main line.  

There are two methods approved for use on SAR to pass knots in a lowering system. The first method uses the belay to momentarily hold the load while the knot on the main is passed through the brake. (Likewise the main will hold the load while the belay line knot is passed through its belay brake.)  It is important to note that the knot is passed through the system brake. The brake is still fully operational except that slack has collected in the area of the brake assembly. If the belay were to fail, the load would fall completely on the main lowering brake regardless of the position of the knot with regards to the brake. It is NOT allowable in this case to disconnect the main brake to facilitate passing the knot through the brake device. If the knot cannot be passed through the brake device then another technique for knot passing must be used. Extreme care must be used to protect the fingers from entrapment in the brake.  

This operation can be done smoothly with no interruption in the lowering flow or can be done in sections by first locking the belay, passing the knot, lowering the belay, and re-assuming the load with the main line. This sequence is depicted in figure-8. For successful and safe operation the system should not arrive at knots on the belay and main line simultaneously.

Passing knots through load transfer to the belay line as is described above has a disadvantage of placing slack in one line which will allow a drop in the load in the event of a failure with the other line. Keeping the amount of slack, and the exposure time to a minimum when the slack is present, minimizes the risk to the operation. Load transfer to belay simplifies the knot passing operation and allows the knot to pass quickly.

A second way, the redundant brake method, is used to pass a knot when personal is limited, when any slack is not acceptable in the system lines due to the integrity of the available anchors, or when the knot will not pass through the brake unless the brake is disconnected. The redundant brake utilizes a second brake, an ascending device (Gibbs or prussik), and an extra section of rope (typically 20 to 50' long). When knot passing will be required, the rope shall be fed through the redundant brake with the running end connected to the ascender as is shown in figure-9. When the knot to be passed approaches the brake, then the ascender must be attached to main lowering line on the load side of the brake. Tension is then applied to the redundant brake until the load is transferred completely to the redundant brake. After the redundant brake has assumed the full load, the knot may be passed through the brake. Since the redundant brake is applied, the primary brake may be removed to facilitate the knot passing. Also since no slack is ever generated in either belay or main lines the result of a single line failure will not highly stress the anchors. Since the redundant brake or the primary brake will alternately assume the load, the redundant brake may utilize the same anchor as the primary lowering system. (It may also have its own anchor if desired.)  The sequence of using the redundant brake is shown in figure-10.

An alternate and equally safe method of applying the redundant brake is shown in figure-11. In this application, the rope is fixed to the anchor using a knot and a carabineer. The ascender is attached to the brake device. The redundant brake operator will then follow the redundant brake  as the load is lowered. The benefit to this style of application is that the redundant brake operator is operating away from the rest of the system which may be beneficial if space is limited. Also the operator is close to the main line attachment area to easily remove the ascender when transfer back to the main line is complete.  

When using Gibbs ascenders as the ascending device, the rule "Keep the fat end of the ascender towards the anchor" applies. This is highlighted in figure-12. When the redundant brake is not required the complete knot passing assembly should be clipped into the main anchor so it will be available and ready to go when it is needed.

PASSING SYSTEM LINES ONTO ANOTHER LOWERING STATION

One major concern of the operations leader is to have the proper rope at the proper site when the lowering is required. In long lowering operations, rescue loads (litters etc.) may be passed from one lowering station to the other. It is easiest and rope efficient to pass the lowering lines along with the rescue load as the operation progresses. In this manner, the same main and belay lines will be used by each station to lower the load. This type of rope passing may be used on low and high angle operations. It is always best to rest the load on a surface during rope transfer. Many evacuations do not offer appropriate ledges or caves when the end of the rope is reached and therefore rope transfer will occur with lowering lines fully loaded.

Figure-13 illustrates the situation where the rescue load will be passed from lowering station "A" to lowering station "B."  In anticipation of accepting the rescue load from station "A" above, station "B" should prepare the anchors needed for belay and lowering. (This chapter highlights the lowering system specifically but notes the importance of the belays that are also used.)  The personal at station "B" assist in passing the load past station "B" with the load still being controlled by lowering station "A."  When the load has passed station "B," progress of the litter shall be halted. Under communication from the operations leader, the main line is slacked to place the load on the belay line. (Note:  That station "A" is slacking its line but still maintaining the rope in the brake which is needed in the event of a failure of the belay line.)  With slack in the main line, station "B" inserts the main line into its lowering brake and places tension on the load. The belay line of station A should be slowly lowered until the main line of station B has assumed the entire load. Again, with coordination through the operations leader, the same procedure is implemented for the belay line. With station "B" now in full control of the rescue load, the main and belay line may be released from the brake and belay at station "A."  In vertical operations care must be taken to toss the line to the sides of the lowering station below. Personnel at station "B" should protect themselves and the subject being lowered from any rock or rope fall that may occur. In low angle operations the rope will just follow along the ground, which helps to alleviate rope twist if a figure 8 brake device is being utilized.  

As an added safety feature, the station accepting the load could have a third, redundant anchor and a short rope section to place the litter in a local locked position while the rope transfer is being made. This provides an added level of security especially when communications are poor as may be the case during a high wind, snowy, night operation.  

In operations where it is not feasible to pass the lowering lines from one station to another, the following transfer technique should be utilized. (This may be needed when multiple subjects must be lowered individually down a long evacuation or when the line are needed to extricate the rescue team.)  In this case, the receiving station should have the lowering and belay lines ready with carabineers attached. The receiving station should have a third redundant anchor to stabilize the load during the transfer and to operate as an extra belay in the event of a problem or a human error. After again allowing the load to pass the receiving station, the redundant anchor is attached and tensioned. This anchor should be attached to the load in a location other than the harness that is being used for the primary system. (This creates redundancy in an area that will not be affected by the transfer.)  The main lowering and belay lines should then be attached to the system harness and tensioned. Slack should then be placed on the lowering station above to fully transfer the load onto the lower station. The main and belay lines from the station above may then be released. One person should open and remove one carabineer at a time to minimize any confusion. (It may seem that a few extra hands will speed the transfer, but it is imperative that the correct cararbineers be removed.)  The extra third safety line should be removed prior to continuing with the lowering station.  

CONVERSION OF THE LOWERING SYSTEM TO A RAISING SYSTEM  

Rescue members should be able to effectively and quickly convert lowering systems to raising systems and the reverse. This may be needed if the load were lowered into an obstacle or a hazardous area that was not seen from above. The actual technique is dependent on the type of raising system that is employed, but the task required is the same. First the lowering station will be "Locked-Off."  The raising system would then be attached to the main line. The lock-off mechanism for the the main line would then be placed on the rope closer to the load than the existing brake. Tension is then released on the brake to transfer the load to the lock-off device of the raising system. The lowering station brake is then removed and attached to a service loop in the anchor or other place where it will be available if the lowering station is needed later.  

OTHER AVAILABLE LOWERING DEVICES  

The Rescue 8 (figure 8) is the primary brake for use on Team1 operations. Limited gear may force the member to utilize an alternate brake system. Also other teams use different types of brakes which should be familiar to the Team1 member to allow joint operations to run smoothly.

If a large rescue load must be lowered by a few rescuers manning the lowering station double rescue 8's could be used to form tighter rope turns, additional friction, and more control. Doubled 8's are applied by placing one 8 on top the other and treating the two 8's as one. A large diameter carabineer is required to attach the 8's as is shown in figure-14.

A braker bar which is an aluminum bar designed to slip over the gate of a non-locking carabineer is shown in figure-15. The friction is generated by the rope passing under the carabineer, over the braker bar, and then back under the carabineer. The benefit of the braker bar is that it makes a brake out of a simple non-locking carabineer (which are not always available in rescue work). Another advantage is that the braker bar does not twist the rope. Care must be taken to place the bar in the proper orientation, as it will fail completely if attached improperly. A braker bar rack is and aluminum or steel bar containing several (5 to 8) braker bars.  

This arrangement is popular in cave entrances and long vertical wall rappels and lowering stations. The multiple braker bar arrangement allows a wide variance in friction and control. The braker bar rack is shown in figure-16.  

When properly adjusted, the operator should be able to control the descent of even large loads with relative ease. The bars must be attached in the proper direction or the rack will fail completely. Also if tensioning is required, (as is needed sometimes at the beginning of a lower when the load decides to return to the top) reversing the direction of the rope flow is very difficult. Breaker bar racks are extremely useful for long lowering operations (1200 ft) with single or joined ropes since the rack does not twist the rope.

A provisionary mode braker bar arrangement can be created by using two locking carabineers (or four non-locking) carabineers as shown in figure-17. One carabineer acts and functions as the braker bar. This carabineer brake arrangement can be applied in series much like the braker bar rack assembly. A six carabineer brake is shown in figure-18. The main advantage of the carabineer brake is that it requires no special equipment (only carabineers) to implement.  

The Military Wrap on a carabineer may be used the same as it would be for rappelling. Care must be used to guarantee that the rope does not walk up and open the locking carabineer. The rope should be attached as is shown in figure-19. The amount of friction increases with the number of wraps that are placed around the carabineer.

For short operations or severe emergencies such as escape from a burning building, the munter hitch may be used as a lower system. Figure-20 indicates the use of a pole and a munter hitch as an emergency brake for a lowering system.  

The braker bar, the braker bar rack, the carabineer brake, the military wrap, and the munter hitch do not provide a simple and reliable means to lock- off the lowering system. For this reason the operator should have an ascender and an extendible webbing section (such as a mariners knot) to lock-off the lowering system if the need arises.  

  
Ventura County Sheriff's Volunteer Search & Rescue  |  Fillmore Mountain Rescue  |  Team 1
Mailing Address:  P.O. Box 296 |  Fillmore, CA  93016
 
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2005 Ventura County Sheriff's Volunteer Search & Rescue, Fillmore Mountain Rescue, Team 1

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