The following information is also based upon the manufactures recommendations of proper aerial stokes set-up procedures, and the teachings of aerial dynamics. Any deviation in setup procedures could possibly damage the aerial or cause an aerial failure during the aerial stokes basket operations. NOTE: The raising and lowering of the stokes litter is through the EXTENTION and RETRACTION of the aerial section. It is critical for all operation to remember that the aerial is NEVER designed as a crane. The applied dynamics to the aerial tip cannot be factored if the operator is attempting to use the aerial as a crane. It would be AGAINST MANUFACTURES RECOMMNEDTATIONS to utilize the aerial in the fashion of a crane or lifting device. All operations must be done within the aerial tip load of the aerial device. Utilizing the aerial in the EXTENTION and RETRACTION mode, will apply a tip load identical to that of the applied load of the patient, and equipment secured to the aerial shown in this set-up fashion. 269
The first step is to position the aerial close to the incident and fully extend outriggers. The Image below shows two 250 rope bags at the base of the pedestal of the aerial device. Bag #1 on the left is the Red Line. This line is the Safety Line for the operation. Bag #2 on the right is the Blue Line. This is the working line for the operation. 270
Using strap to secure rollers. Keep load in the center for a neutral axis Lights may prevent roller from being installed at the tip. Rollers may not fit at the tip because of light (s) placement. This will not compromise the stokes operation or aerial physics For any column there exists a line known as the neutral-axis, such that any force applied through the neutral axis results in only axial displacements (no twisting about the axis), otherwise any force not passing through the neutral axis results in some twisting. Bring both lines to the tip. The ladder may be lifted and moved slightly off center for an easier installation. 271
Aerial Litter Basket Set-Up Run both lines over the rollers and drop the lines down for the stokes to be connected. Ropes shall drop after the roller do not extend to the last rung if the rollers are not placed on the last rung Keep lines centered to maintain a neutral axis. Connect both lines to the Stokes Litter with a four point pre-rig. The pelvic lashing shall be used any time the foot of the litter is lower than the head. The chest lashing shall be used on all victims during a high angle rescue. Exterior lashing shall be used at all times. Rescuers and victims shall always be attached to the rope system itself, not just the litter, during steep and high angle operations. 272
a.attach the four point pre-rig to the top rail of the litter with the carabiner gates facing downward and inward. b. Adjust the prusik loops to level the litter. c. Attach the main and belay lifelines to the steel O ring of the pre -rig. 273
Double Figure 8 The connection with the four way pre-rig 274
The safety/lowering device set-up. Securing the ropes to the ladder Raise ladder to 60 degrees Before securing the lines at the base of the ladder raise the aerial to 60 degrees and 55 foot extension. This will give you the most options later when moving the Stokes Litter Extend ladder to 55 feet 275
The safety/lowering device set-up. Securing the ropes to the ladder Red Line (Safety Line) Blue Line (Working Line) On the Left is the RED LINE set-up. The set up included a large locking carabineer connecting to the safety line by a prussik. The Blue Line set-up. The set up includes a large locking carabineer connected by green webbing to the base of the aerial connecting to an 8-plate. The working line is attached to the Figure-8 276
A load releasing hitch in the system is not necessary, if the load releasing hitch is used then store assembled (pre-rigged). Secure at the base with green webbing 277
Tag lines should be used to prevent the litter from twisting and/or coming in contact with obstructions during vertical rescues. For short distances under 80 feet, the drop bag rope may be used. For longer applications the lifeline may be used. Pull the tag line only enough for the litter to just clear the obstacle. Attach to the top rail of litter with a running loop using the hook of the drop bag rope. If using a lifeline, attach it with an unlocked carabiner. Do not use as a crane/ Do not exceed 500 lbs. at the p If the load gets snagged, the hydraulics don t know and just keep working a person would let go, but machines aren t that smart. it s not the weight but the tension in the e off ropes or cables that ma er. Elas c nature of the ropes or cables causing shock loads. Do not use if uneven loading of the weight resul ng in twis ng of the ladder 278
Do not use a crane. Use with the methods shown here, and never exceed manufactures tip load tables found on the pedestal. Utilizing the aerial in the EXTENTION and RETRACTION mode, will apply a tip load identical to that of the applied load of the patient, and equipment secured to the aerial shown in this set-up fashion. Do not use a pulley below the tip. This will double the weight at the tip. An operator might say what is the difference between having 250 lb on the ladder and having 250 lb suspended below the ladder? The obvious answer is that First is how the load is applied, is it applied through the width of the rope or cable, or is it distributed over a broad area (pressure comes into play which equals stress as in the stress-strain curve). Secondly, is the load centered? If not properly applied, twisting the ladder results, which is more likely when loads are suspended by ropes or cables, rather than by placing the load on top of the aerial. Thirdly, if you lift a 250 lb object which is attached by some sort of rope or cable, the elastic nature of the rope or cable comes into play, not to mention the acceleration of the object. Realize, that to lift a 250 lb object by a rope or cable requires a tensile force of more than 250 lb (a tensile force of 250 lb simply balances the weight, to lift up requires more) and the rate the load is accelerated amplifies the effect. And finally, the elastic nature of the rope or cable adds its own acceleration component. Because many of these items are not really controllable by the operator and can result in substantial increases in the forces acting on the aerial, the engineers at the manufacturers insist that the loads are not applied inappropriately and so ensure the statements are included in the operator s manual. 279