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Ian Matthews
Join Date: Jan 2006
Location: Melbourne Australia
Posts: 3,218
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In regard to your 4WD basics, this is the manual for training of emergency services personel. If you read it, you will note that it instructs some points that I have previously and continue to disagree with. But I have posted the manual complete and have not edited it.
The moderators may wish to use this as 4WD basics information.
EMERGENCY MANAGEMENT AUSTRALIA
AUSTRALIAN EMERGENCY
MANUALS SERIES
PART IV
Skills for Emergency Services Personnel
Manual 8
FOUR-WHEEL-DRIVE
VEHICLE OPERATION
CHAPTER FIVE
4WD TECHNIQUES
INTRODUCTION
5.01 Before attempting to negotiate difficult terrain, it is essential to first assess the situation. Different types of terrain require different techniques; experience has shown the following techniques are effective. In very rough uneven terrain, use low range 4WD. This will lower speed, reducing the vehicle's bounce, and will give better steering. The following general principles apply to most situations:
a. Select the appropriate gear before attempting an obstacle.
b. Do not change gears whilst crossing an obstacle.
c. Drive steadily.
d. Keep good throttle control to reduce wheel spin.
e. When wheel spin occurs, always decelerate; never accelerate.
DRIVING IN MUD AND SAND
5.02 DRIVING IN MUD
Stop before the mud begins. Physically check the obstacle on foot and decide on the best route.
5.03 When driving in mud or slush the most efficient method is to select H4 first or second gear and maintain a constant but moderate speed which will ensure momentum for negotiating the softer sections. Do not exceed about 25 km/hr as the ability to steer the vehicle is greatly reduced. Momentum is more important than power.
5.04 Avoid changing gears and revving the engine when traction is lost. If forward progress is halted declutch immediately and select neutral to avoid digging in. Assess the situation. Take appropriate recovery action, do not try to ‘spin your way out' as it can cause serious damage to the vehicle, particularly if it
is fitted with a limited slip differential. If bogged try rocking the vehicle by
alternating between forward and reverse gears.
5.05 If the wheels are spinning on a hard, slippery surface, deflating tyres to about 100 kPa (15 psi) often helps to increase traction and assist recovery.
The following points should however be noted:
a. If tyres are deflated, be sure that you can re-inflate them afterwards.
b. Consider use of chains to provide extra traction, fitting them to all the
wheels if possible. If only one pair is available, place them on the front
wheels to improve steering as well as traction.
5.06 ASCENDING WET SLOPES
Driving up (or down) hill in wet and muddy conditions is particularly hazardous. Should traction be lost during an ascent, simply use the stall recovery procedure. (See paragraph 5.39). This will enable control to be regained. Avoiding the situation is much better than trying to correct it.
5.07 DECENDING WET SLOPES
When driving down hill in wet, slippery conditions, select L4 first gear—avoid
applying the brakes if possible. Allow the vehicle to descend under engine
braking. Changing direction is effected by slight corrections of the steering
wheel and a gentle ‘stab' of the accelerator. Avoid large steering wheel
movement as this often leads to rear end skid and its inherent dangers of roll
over.
5.08 CONSUMPTION CHECKS
Watch closely for increases in oil/fuel consumption and coolant temperature in prolonged driving through mud.
5.09 DRIVING IN SAND—GENERAL
As with driving in mud, momentum is more important than power when driving through loose sand. Use 4WD, high range where momentum is required. The two kinds of sand driving coastal (beach) sand; and inland (dune) sand. Each demands similar driving techniques but each have different hazards which need assessment.
5.10 DRIVING ON BEACH SAND
Before driving along a beach:
a. determine the present tide situation (high or low);
b. determine when high tide is due;
c. assess how far up the beach the water will come at high tide; and
d. assess alternative access points.
5.11 While driving on a beach stay to the wet sand just above the water line. Do not accelerate or decelerate rapidly as wheel spin can break up the packed sand resulting in bogging. Watch for rocky outcrops and other hazards and soft sand at the mouth of streams.
5.12 Deflate the tyres to about 100 kPa (15 psi) before driving on soft beach sand. This is often necessary to get on and off the beach. After tyre deflation, restrict speed to 20 km/hr.
5.13 DRIVING ON INLAND SAND
Before driving across inland sand consider:
a. prevailing winds;
b. texture of the sand (fine or rough/wet or dry); and
c. type of vegetation (mallee roots will spike tyres).
5.14 When crossing sand dunes drive straight up the incline (whenever possible). Stop at the crest and examine your descent path, prevailing winds tend to shape sand dunes like ocean waves and a vertical drop may be obscured.
5.15 When descending a dune use L4 first gear and steer directly down the incline. DO NOT touch the foot brake. If you need to steer the vehicle use the same technique as used in steering in mud, a small change in steering wheel direction and a sharp, short ‘stab' of the accelerator. Minimise steering changes when descending sand dunes as a rear end skid is likely.
DRIVING IN WINTER CONDITIONS
5.16 Driving on roads covered with snow or ice can be hazardous due to the lack of traction. Great care must be exercised when driving in these conditions.
5.17 WINTER DRIVING TECHNIQUES
Drive slowly. Maintain large distances between vehicles. A four second time gap is recommended when driving in winter conditions so as to ensure sufficient stopping distance.
When driving in winter conditions:
a. braking can be hazardous. Keep speed to a minimum and brake smoothly;
b. use accelerator, clutch and steering wheel smoothly;
c. drive cautiously and be aware that the vehicle could go out of control at any time;
d. expect other vehicles to go out of control at any time;
e. for an emergency stop, drive the vehicle into a snow bank or other obstacle;
f. don't apply the handbrake when parking the vehicle (brakes could seize up due to the cold);
g. lift windscreen wipers off the windscreen when the vehicle is parked so they don't freeze to the screen;
h. add methylated spirits to windscreen washer reservoir to avoid the water freezing; and
i. keep the fuel tank as full as possible (this reduces water condensation).
5.18 SLIPPERY SURFACES
Slippery surfaces can be caused by compaction of the ice or snow. You may also find ice on bridges, in road cuttings, under tree overhangs, in any shadow or shaded areas or in water run-off areas. Icy surfaces can also be caused by low temperature fog, or rain followed by a frost. Ice on the road can be very difficult to see, drivers therefore need to be aware of potential dangers.
USE OF CHAINS
5.19 If chains are required, they should be fitted to all four wheels. If only one set is available then fit them to the front wheels.
5.20 DRIVING WITH CHAINS FITTED
Do not use the full extent of the steering lock, as the chains may rub on the guards etc. Drive slowly, and expect the wheels to be out of balance. Chains increase stress to the vehicle's drive line components as they generate shock loading throughout the drive line. Some vehicle manufacturers may void vehicle warranty if chains are used while the vehicle is under warranty, check with your dealer.
DRIVING IN SNOW
5.21 GENERAL POINTS
a. Assess the situation and check type of snow (wet, dry, ice crust, compacted).
b. Fit chains. (In marked bays or safe areas)
c. Check depth of snow; generally a vehicle can negotiate powder snow that is twice the depth of heavy wet snow.
d. Check the distance to travel, and look for possible snow drifts further along the road. (You may have to reverse all the way out.)
e. Check where the road is under the snow.
f. Don't ‘bury' the vehicle by spinning the wheels.
5.22 PROCEDURE IF BOGGED
a. Dig out snow around vehicle. Pack down a track, including between wheel tracks.
b. Try to rock the vehicle out by alternating between forward and reverse gears.
c. Choose the more favourable direction, (forward or backward), to free the vehicle.
d. Consider jacking the vehicle and placing something firm under the wheels (branches, boards, etc). A base plate for the jack will probably be necessary in this situation.
DRIVING ON ROCKY TERRAIN
5.23 Driving over rocks is mechanically demanding on the vehicle and requires a high level of concentration from the operator. Before driving over rocks consider an alternative route, if not available, then walk and mark the chosen route, shifting small rocks to fill holes and make the path as even as possible;
5.24 ROCK-CROSSING TECHNIQUE
When crossing rocks use the following technique:
a. Use L4 first gear.
b. Use throttle control to ‘walk' the vehicle over the rocks.
c. Ensure both hands are gripping the steering wheel, slightly tense up the arm muscles to resist wheel deflection—thumbs outside the wheel rim.
d. Allow the vehicle to ‘inch' its way across.
e. Make changes of direction as necessary to prevent the vehicle ‘hanging-up'.
5.25 INSPECTION AFTER CROSSING ROCKS
Thoroughly inspect the vehicle after crossing rocks, paying particular attention to:
a. brake pipes and hoses, (for fractures);
b. steering linkages, (for damage); and
c. tyre walls, (for cuts).
WATER CROSSINGS
5.26 Driving a vehicle through water is a hazardous exercise at the best of times, and care must be taken to ensure a safe crossing. Although your 4WD has features that enable it to cross water more easily than other vehicles—such as its greater ground clearance—too much water will stop any 4WD vehicle. This may happen as a result of:
a. water entering the electrical system or air intake;
b. loss of traction due to the nature of the bottom; or
c. loss of traction resulting from vehicle floating off or being washed off the bottom. Where this occurs it may be necessary to open a downstream door to ‘sink' the vehicle.
5.27 OBSTACLE ASSESSMENT
Stop and assess the obstacle before committing yourself to it. Be sure that you have to negotiate the water crossing. You may be better off spending extra time on a longer route.
5.28 Never drive into water of unknown depth or unknown bottom surface condition. Walk the crossing first, if necessary and safe to do so. Always determine for yourself the:
a. current strength;
b. water depth, (do not enter deep and/or fast water);
c. bottom conditions; and
d. location of obstacles.
5.29 PLANNING AND PREPARATION
Mark all obstacles on the bottom (rocks, logs etc). Decide on the entry and exit points and stick to them. If possible identify a suitable anchor for a winch rope in case this is needed for recovery and consider access to recovery equipment if required. Always try to have the exit point slightly up stream from the entry, to maximise bow wave effects.
5.30 BOW WAVE TECHNIQUE
If water reaches to the bumper bar or higher, upon entering the water accelerate until a bow wave forms in front of the vehicle. Maintain this bow wave at all costs, to keep water out of the engine. Try to keep a steady pace using constant engine revs. The bow wave will keep water from entering the engine compartment; this technique will only be successful if the river bed is relatively smooth.
5.31 DEEP WATER PREPARATION
If water depth is greater than about 750 mm, prepare the vehicle as follows:
a. Place a canvas sheet/tarp or hessian bag across the grille to prevent
water entering the engine bay.
b. If available, fit a snorkel extension to the engine air inlet and exhaust
systems.
c. Spray the ignition system with de-watering fluid.
5.32 WATER CROSSING PROCEDURE
To negotiate an expanse of water use the following procedure:
a. Select L4 first gear (L4 second gear if the bottom is sandy).
b. Position the vehicle with the front wheels on the embankment and just in the water.
c. Enter and cross the water without stopping. A slight increase in engine revolutions may be needed to maintain the bow wave. Where the bottom is rough or rocky it may be advantageous to set the hand throttle.
d. Do not touch the clutch while the vehicle is in the water as this may allow water to enter the clutch and slippage to occur.
e. If wheel spin occurs, select neutral without using the clutch and carry out recovery as necessary. Do not ‘switch off' the engine while in the water.
5.33 CROSSING EXIT
Allow only one vehicle in the water at a time and clear the exit point for each vehicle. ‘If possible ease off throttle as vehicle exits crossing; this will reduce bow wave erosion effects on exit ramp from water. This has a significant effect on well-used crossings, and improves the chances of rear vehicles in a convoy completing a successful crossing in marginal exit ramp situations.'
5.34 Dry out the brakes as soon as the crossing is completed by driving with light foot brake application.
5.35 If a lot of water crossings are made, as soon as possible afterwards, have the condition of the oil in both differentials and gear boxes checked. If the oil is found to be a milky white colour, it means that water has contaminated the oil.
NOTE: After deep water crossings, the vehicle must be serviced as soon as possible.
DRIVING IN OPEN GRASSLAND
5.36 HIDDEN DANGERS
4WD may not be required for driving in open grassland. However, there are still many things for a driver to consider in what may appear to be the easiest of off-road driving conditions.
a. Avoid the temptation of travelling at high speeds, as grass can and does hide many hazards.
b. When driving in long grass, especially with long nosed vehicles, it is prudent to have someone walk in front of the vehicle to detect holes, stumps, rocks etc.
c. In fire conditions, the added problem of smoke can reduce visibility to almost zero, thus increasing the possibility of collision.
d. Be aware of the danger of vehicle exhaust causing a fire.
e. Be aware of engine overheating due to grass fouling the radiator core.
NEGOTIATING BURNT GROUND
5.37 When operating on ground recently burnt be aware of the dangers that exist to the vehicle through:
a. hot spots which may cause tyre or other damage;
b. ash intake into engine air cleaner and vehicle cabin;
c. falling branches from fire-damaged trees;
d. downed power lines;
e. tyre damage (side wall) due to staking;
f. entanglement in fencing wire; and
g. engine overheating.
NEGOTIATING STEEP TERRAIN
5.38 ASCENDING STEEP SLOPES
Always aim for a successful first ascent. Recovery from failure can be difficult and dangerous. Use the following procedure:
a. Stop and look.
b. Check the grade before you commit yourself.
c. Look at surface condition and exit point.
d. Choose the appropriate gear.
e. Approach a steep grade square on. Do not traverse across the slope.
f. It is important to select the required gear before you attempt the ascent. When in doubt use L4 first gear.
g. Use a slow and steady approach. By approaching the grade in the correct gear with engine revs at maximum torque, the vehicle will steadily climb the hill without problems.
h. If wheel spin occurs it may be reduced by slightly turning the steering wheel repeatedly from side to side so as to use the lugs of the tyres to gain extra traction. Gently pumping accelerator may also assist by creating a ‘spin-grip' action by the tyres on the track surface.
5.39 STALL-STOP AND RECOVERY
When ascending steep slopes, if progress is halted due to obstacles or loss of traction, use the following procedure to stop and recover to a safe area:
a. Release the accelerator, apply the foot brake firmly and hold it on, and allow the engine to stall in gear— Do not use the clutch
b. Apply the hand brake and turn the ignition off.
c. Recover your thoughts and plan your actions.
d. Ensure the track is clear behind you and select an aiming point.
e. Gently depress the clutch, so as to ensure that the brakes are holding the vehicle, select reverse gear, release the clutch. If the gear will not engage hold the lever against the gate and flick the key to start position and back to the off position, the gears will align and engage without difficulty.
f. Release the hand brake if applied. Ease off the foot brake allowing the vehicle to rest on the gears, do this gently as vehicle movement will occur as the gear train slack is taken up.
g. While looking into the rear vision mirrors, turn the key to ‘start' and allow the engine to start with the clutch engaged.
h. Allow the vehicle to descend under engine braking and control the speed with the foot brake as needed until you reach the pre-selected safe place.
i. If during the descent to a safe place, you become concerned for the safety of the vehicle apply footbrake to stall the vehicle in gear. Reassess the situation and repeat procedure as appropriate.
5.40 DESCENDING STEEP SLOPES
Adopt the following safety procedure for steep decents:
a. Stop at the top and look.
b. Check the gradient before committing yourself.
c. Walk down the hill if you cannot see the bottom, or any section.
d. Adopt a ‘square-on' approach.
e. Use low range 4WD first gear; do not change gear on the hill.
f. Allow the vehicle to descend on engine compression. Gently apply brakes to maintain safe speed.
g. If wheels begin to skid, keep front wheels pointing down hill. Gently ease off brakes to get wheels rolling again, then gently re-apply brakes.
h. The stall-stop and recovery technique can be used to regain control of the vehicle if necessary.
5.41 PLANNED STOPS ON STEEP SLOPES
If you need to stop on a very steep slope use the following procedure:
a. Turn ignition off.
b. Apply the foot brake, stall the vehicle in gear. Do not touch the clutch.
c. Apply the hand brake.
d. If you have to get out of the vehicle, engage first gear (if not already engaged) and chock all wheels.
5.42 STARTING ON STEEP SLOPES
When restarting on steep slopes there are three alternative methods that may be used, these are:
a. Key Start —As described in stall-stop procedure and used for all downhill restart situations. This technique is not suitable for uphill starts.
b. Hand Brake Start —Used for uphill situations, as follows:
(1) With the vehicle stopped, in gear and foot brake applied, apply the hand brake.
(2) Depress the clutch and select L4, first gear, start the engine and release the foot brake.
(3) Now, using the accelerator to control engine speed, bring the clutch to ‘friction point', release the hand brake and drive off.
c. Throttle Start —Used for uphill situations, as follows:
(1) With the vehicle stopped, in gear and foot brake applied, depress the clutch and select L4, first gear.
(2) Start engine and increase RPM to an appropriate level (say 1500 to 2000 RPM) using the hand throttle.
(3) Engage the clutch to ‘friction point'. Release the hand brake and gently release the foot brake allowing the vehicle to move off by simultaneously releasing the clutch.
(4) Release the hand throttle as soon as you are in control.
WARNING: Do not ride the clutch during these procedures, ie fully release the clutch as soon as possible .
5.43 CROSS SLOPE DRIVING
Avoid side slopes whenever possible If you must drive across a slope be alert to the inherent danger of the vehicle losing traction and slipping sideways. An apparently safe (10 to 15 degrees) side slope can quickly become dangerous should the low side wheels drop into a small stump hole or the high side wheels ride up over a rock, log or mound.
5.44 SHORT VERTICAL RISES
A 4WD vehicle can negotiate a short vertical rise provided that the front bumper bar or front spring hangers can clear the top of the rise. Ensure that beyond the rise there is a relatively even surface longer than the vehicle's wheel base to avoid it becoming ‘high-centred' or ‘hung-up':
a. Ascending:
(1) Stop and assess the situation. (Do you have the necessary clearance?)
(2) Use L4, first gear.
(3) Adopt a ‘square-on' approach. Both front wheels must climb the rise simultaneously.
(4) Move slowly and steadily allowing front wheels to climb the obstacle. When front wheels are on top of the rise, back off the accelerator.
(5) It may be necessary to maintain some vehicle momentum to assist the rear wheels over the obstacle.
b. Descending:
(1) Stop and assess the situation.
(2) Use L4, first gear.
(3) Adopt a ‘square-on' approach.
(4) Move slowly and steadily allowing the vehicle to creep over the obstacle. Do not touch the clutch.
(5) Gently apply foot brake if needed to allow a slow and controlled descent. Do not ‘lock-up' the wheels.
5.45 HUMPS AND DITCHES
Approaching at an angle assists when negotiating ditches or humps that are narrower than the length of the vehicle. However you must be careful not to ‘high-centre' the vehicle (that is, strand it on a hump with all wheels off the ground) and watch for excessive chassis twisting.
5.46 The technique is the same as that for ‘short vertical rises' except that engine power is kept steady while the obstacle is crossed. When crossing water drains or wash-aways ease off the accelerator as the front wheels cross the hump to avoid becoming airborne.
BRIDGE ASSESSMENT/CROSSING
5.47 Situations may arise where drivers need to cross a bridge of unknown or doubtful condition and strength. The following points should be considered in assessing the bridge:
a. Look for load limit signs.
b. Check approaches for:
(1) solid ground;
(2) slopes and grades; and
(3) wash-outs etc.
c. Check decking for:
(1) holes;
(2) loose planks;
(3) split or broken planks;
(4) rotting sections of timber;
(5) loose or missing bolts;
(6) spikes;
(7) adequate width; and
(8) sufficient thickness of planks to carry load.
d. Check beams for:
(1) size and strength;
(2) support at ends; and
(3) signs of overloading or failure (sagging, splitting).
e. Check pylons for:
(1) rotting;
(2) bracing;
(3) connections to beams;
(4) damage caused by flood/floating objects; or
(5) damage caused by fire.
f. Check abutments for:
(1) washout of abutment; and
(2) gaps, or displacement of beams.
g. If in any doubt about the bridge, consider whether there is a better way to cross?
h. Test the bridge by slowly driving onto it with a guide watching and listening for signs of failure (cracking and movement).
CHAPTER SEVEN
RECOVERY
INTRODUCTION
7.01 In regard to 4WD operations, recovery is the safe and successful extrication of an immobilised vehicle. It should be noted that speed is generally not a consideration in recovery operations.
REASONS WHY VEHICLES BECOME IMMOBILISED
7.02 When vehicles are required to travel across country, there is a real possibility that they may become immobilised. The reasons for this situation are many and varied; here are some examples:
a. Poor reconnaissance, involving:
(1) lack of knowledge of the ground or route; and
(2) poor appreciation of the terrain.
b. Poor driving and lack of care for the vehicle.
c. Stopping on poor surfaces.
d. Mechanical breakdown.
SAFETY
7.03 The driver is responsible for the vehicle and directs the recovery operation. Recovery work is arduous and often calls for considerable physical effort, however, an element of danger is often present. This danger can be minimised by proper direction and teamwork.
7.04 HAND SIGNALS
If hand signals are used they need to be understood by all involved.
WINCHING OPERATIONS
7.05 COMMON WINCHES
There are three different types of winches in common use:
a. Power Take-Off Winch —This winch is powered from the vehicle's transfer case, via a drive shaft to the winch's worm drive. It can only be fitted to vehicles equipped with a power take-off facility
b. Electric Winch —This consists of an electric motor (similar to a starter motor), a worm drive and drum. It can be fitted to any vehicle. The winch is powered by the vehicle battery. It has the disadvantage of drawing enormous amounts of current from the battery when in operation. The fitting of dual batteries to vehicles with electric winches is recommended.
c. Hand-Operated Winch —A number of these are available, including brands such as ‘Tirfor', ‘Anchor', ‘Elephant Looper' and ‘Thomas'. These are portable, hand (lever) operated winches. They can be easily carried and operated by one person, and come with their own cable and extension handle.
7.06 OPERATING HINTS
a. Become thoroughly familiar with the winch's operation before you are forced to use it to get out of trouble.
b. For power take-off winches, always carry spare winch shear pins (use only genuine shear pins).
c. The winch cable should never be used for towing, even for a few metres. It could result in damage to the cable and winch.
d. Always pull in as straight a line as possible. The fairleads are designed to help with minor misalignment, but cable strength is severely reduced when forced to go around a corner.
e. Use the winch control switch or operating lever intermittently to take up cable slack and avoid shock-loads which can momentarily far exceed the winch and cable rating.
f. Always stop winching when the hook is about a metre from the fairlead. Use the winch control switch intermittently to spool in the remaining cable.
g. When using an electric winch, keep the vehicle engine running slightly above idle speed if possible, to provide charging for the electrical system.
7.07 DIRECT PULL
The direct method is the most commonly used. Never wrap the winch rope around the anchor point and back onto itself. Not only is this a dangerous practice, but can cause permanent damage to the winch rope. Always use a sling. This direct pull method is suitable only when the maximum possible loading does not exceed the rated safe maximum winch load.
7.08 DOUBLE PULL
This method is used to gain a mechanical advantage. It is referred to as a 2 to 1 pull (2:1). Using a double pull may reduce the amount of force required from the winch to achieve the pull which in turn will result in the winch drawing less amperage than a single pull and therefore may be more appropriate for use with an electric winch in some situations.
7.09 CHANGING DIRECTION OF PULL
This is when a SWR block is used to change the direction of pull. Mechanical advantage can then be obtained if required by attaching another snatch block to the load and running the winch cable back to the anchor point.
7.10 SAFETY PRECAUTIONS (POWER WINCHES)
The following safety precautions are to be observed prior to and during a winching operation:
a. One job, one boss.
b. Check that all equipment is serviceable.
c. Always wear gloves when handling wire rope and chains.
d. Don't disengage the winch dog-clutch when the rope is under strain.
e. Check the hook-up before and once strain is taken up.
f. Ensure sufficient rope remains on the drum. (Normally six to eight turns. Check the manufacturers handbook).
g. Don't walk behind a vehicle being winched up an incline.
h. Ensure that signals if used are understood by all involved.
i. Keep all personnel out of the rope danger arc (1.5 times the length of payed out rope).
j. When re-engaging drive to a winch under strain, do so slowly.
k. Never step across or stand over a winch rope or attached equipment whilst under strain.
l. Never exceed safe sling angles.
m. Snatch blocks, rope etc should not be allowed to drag through the earth, rollers or skidding should be placed beneath the ropes.
n. Place a bag, blanket or similar over the middle of the cable so that in the event of the cable breaking it will wrap around the bag and reduce whiplash.
o. Always be aware of the manufacturers specifications and safe working loads, and operate the winch within those parameters.
p. Do not hook the winch rope back over itself as this reduces the safe working load by up to 50% and damages the rope. Use an approved chain, wire or synthetic rope sling.
q. Do not handle the cable closer than 750 mm from the drum when winching. A loose wire may snag the glove and draw the operator's hand into the winch.
r. Do not use the winch for lifting casualties.
s. Damaged wire ropes must be replaced.
t. Winches must be mounted on vehicles in compliance with the manufacturers specifications and state/territory regulations.
u. Some winches have a shear pin, which is designed to shear if the winch is overloaded. The shear pin should only be replaced with a genuine replacement pin.
v. When winching, where possible, keep the cable straight ahead of the winch while under load.
w. Before applying a load to a new wire rope, it should be run out to the last five turns on the drum and spooled onto the winch under a load.
x. Always take out the slack in the rope before applying full power to the winch. Sudden jerks may exceed safe working loads.
y. With a PTO winch, do not release the vehicle clutch rapidly as it could shear the safety pin.
z. Always wind the cable tightly. A good method for winding the cable is to extend it fully, attach it to a holdfast, and then pull the vehicle with the brakes lightly applied. Wind the entire cable with this load.
7.11 SAFETY PRECAUTIONS (HAND WINCHES)
Safety precautions specific to hand-operated winches:
a. If a single operator cannot move the load with the telescopic operating handle fully extended, the load is too great for the machine and a steel wire rope block should be used to increase the mechanical advantage. The operating handle must not be extended in any way.
b. Always use slings and anchors of sufficient strength to withstand the load.
c. Keep the wire rope wound onto the reeler when not in use.
d. Never allow any kinks in the rope to enter the machine as this causes internal damage.
e. Only use the wire rope supplied with the machine.
f. Never anchor the machine by the tip of the hook, always use a sling.
g. Never apply tension to the running end of the rope.
7.12 NATURAL ANCHORS
A large tree is probably the best anchor to use. Ensure that the tree is strong enough to withstand the load you intend to put on it.
7.13 It is important that you do not damage a living tree or its bark while it is being used as a anchor. The best way to minimise tree damage is to use a web sling. The web sling is placed around the tree, as low as possible. If you intend to use a wire sling or chain around the tree to secure the winch cable, to prevent damage to the tree and possibly ring barking the following precautions can be used:
a. Place a hessian bag or similar material between the sling and the tree.
b. Place a number of small pieces of timber upright around the tree between the sling and the tree trunk.
7.14 If a tree is considered not to be strong enough by itself, it may be practical to strengthen the anchor by placing the sling around two or more nearby trees to form a strong collective anchor.
7.15 STAKE/GROUND ANCHOR
This method is effective as an anchor point where no other suitable points are available. The materials required to construct this anchor are three or four steel pickets and a sufficient length of cordage. The pickets are driven into the ground on an angle. The cordage is then wrapped around from the top of one picket to the bottom of the other. The winch cable is then anchored using the chain. If the pickets pull out they will be required to be driven further into the ground or more pickets used
7.16 ‘DEAD MAN ANCHOR'
The ‘dead man' is used where the ground is suitable, but it must be remembered that its construction requires a large effort. Maximum resistance depends on: a. the strength of the buried timber; and b. the resistance of the earth.
7.17 In good ground, a trench is dug 1 to 1.5 m deep. A log or timber approximately 400 mm thick is placed in the trench or the vehicle spare wheel may be used as an alternative.
7.18 The angle of the cable exit to the anchor trench must never be any greater than 30 degrees from the horizontal plane, less if possible, as the smaller the angle, the more earth there is providing resistance
7.19 BACK-TIE
Caution should be exercised when using a winch mounted to your vehicle to recover another vehicle which is bogged. Owing to the enormous resistance created, the bogged vehicle becomes a hold fast toward which your vehicle will be drawn unless the resistance is overcome. Depending on the circumstances it may be necessary to back-tie your vehicle (using a conventional hold fast method) or, in extreme cases deliberately (temporarily) bogging your vehicle.
7.20 MINIMUM RECOVERY WINCHING EQUIPMENT
a. Web sling about 3 m long, fitted with eyes both ends, nylon or similar material; appropriate capacity.
b. Snatch block of 100 to 150 mm diameter single sheave, appropriate capacity.
c. Short wire rope sling, 1 m long, fitted with eyes both ends, appropriate capacity.
d. ‘D' shackles, appropriate capacity.
e. Leather gloves.
7.21 SLINGS
Refer to Figure 4.3 for information on safe sling angles.
7.22 For additional information on the subjects of ropes, winches and anchors,
refer to AEM—Disaster Rescue.
JACKING OPERATIONS
7.23 PRELIMINARY CHECKS
Check the following:
a. Does the vehicle have a jack?
b. How does it work?
c. Have you got a jack handle, and a wheel brace to undo the wheel nuts?
d. Do they fit the vehicle?
e. Where are the lift points on the vehicle?
f. How high does it lift?
g. Do you have a jack base plate?
7.24 JACK PLATES
For jacking a 4WD vehicle, a jack plate is almost essential. This is a piece of timber (20 to 25 mm thick plywood is best) approximately 250~`mm square. It is used as a base for the jack when jacking on soft or uneven ground.
7.25 HIGH-LIFT JACK
A high-lift (Wallaby) jack can be used to lift one end of a vehicle up to a metre off the ground to enable rocks or timber to be placed under a bogged or stuck vehicle so it can regain traction. In addition, a high lift jack can be used to lift one end of a vehicle off the ground so it can be pushed sideways to gain firmer ground. This jack in conjunction with chains and cable can also be used for winching.
7.26 To be able to use a high-lift jack skilfully a little practice is needed. Practice before you are forced to use it in a real life situation.
7.27 SAFETY INSTRUCTIONS
Before using any jack refer to the manufactures instructions to familiarise yourself with the safe operation of the jack.
7.28 HIGH-CENTRING RECOVERY
Should the vehicle ‘bottom out' on a rock and become high-centred, the following procedure applies:
a. Switch off engine and leave in gear with the hand brake on.
b. Jack up the wheel most likely to provide necessary clearance. In doing this ensure:
(1) the wheels are chocked;
(2) the jack is stable;
(3) the jack is high enough to just clear the obstacle—do not raise the vehicle more than necessary; and
(4) you have packed under the wheel with suitable material.
NOTE: Jack up the lower side rather than the higher side (if roll over is likely, secure the vehicle using suitable rope and/or a winch before jacking).
c. When clearance has been gained, remove the jack and wheel chocks, then ‘inch' the vehicle over the obstacle.
SNATCH-EM-STRAP
7.29 A snatch-em-strap is a type of webbing tow rope that can be stretched like a rubber band. The snatch-em-strap allows the towing vehicle to build up momentum, and use the momentum combined with the vehicles normal power to pull a vehicle out of a bog.
7.30 DANGERS IN USAGE
Snatch-em-straps can result in considerable dynamic loads. This has been known to cause tow bars to be sheared and flung into windscreens and ‘D' shackles to be torn from mounting points and propelled through vehicle body panels. Only trained personnel should use this device.
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