DIGGER DERRICK OPERATION

OBJECTIVE

You will be given a self study session on the operation of a Digger Derrick to lift loads, set a pole and install and anchor. In the field you will perform various lifts and install a PISA, under the supervision of your foreman.

INTRODUCTION

The digger derrick has become the workhorse of the line crew. With it a great number of functions may be performed. It is used continually as a device lifting a wide variety of loads from transformers to reels of cable.

The digger derrick is also equipped to auger pole holes, to set poles, to install power installed anchors (PISA) and to operate several hydraulic tools i.e. pole tamper, pole jack, hydraulic presses etc.

INSTALLING A POLE

In a later module you will be learning how to installing a pole, using an digger derrick, at a staked location. Before the actual digging begins, there are a number of things that must be checked and reviewed. Make sure that all utilities are located and marked.

The first check will be the digger derrick. This will involve a review of the Driver’s Daily Circle Check, inspection of the unit, of stability and safe operation of the unit.

To operate a digger derrick or direct the operation of a digger derrick, you must understand a standard set of directions that are given by hand. This is necessary because of the noise of the equipment or traffic. The coordinated effort of an operator and signal person is a must, to work safely in an electrical environment.

Before you can install the poles, they must be transported to the work site. Transporting poles involves connecting the trailer, loading the poles, and binding the poles on the trailer. This job can be very hazardous. Tail Board Conference, prior to loading is a must, with continuous communication between all parties.

The loading, unloading and storage of poles (wood and concrete)

presents many hazards to the workers involved. Hazards associated with this work usually occur when the pole-pile shifts suddenly. The danger of poles rolling or falling is greatest at this time. The following information will outline a procedure to follow when handling poles.

PRECAUTIONS FOR HANDLING WOOD POLES

Observe the following:

a)         Poles should be handled from the end of the pile. Workmen should not climb on the pole-pile needlessly.

b)         Handle poles with cant hooks or pry bars.

c)         Keep clear of suspended loads to prevent injury if the load swings unexpectedly.

d)         The workman attaching the chocker/Sling to the pole will place himself in the safest possible position. Do not stand

between the pole and the lifting device the digger derrick.

e)         Attach the winch cable as closely as possible to the balance point of the pole. In some cases the pole will have to be blocked to facilitate reinstallation of the winch cable closer to the balance point.

f)          When handling wood poles, attach the chocker/sling securely so they will not pull free when the winch cable is tightened. 

PRECAUTIONS FOR HANDLING CONCRETE POLES

When handling concrete poles, much heavier weights are involved. These poles should be handled carefully to avoid bending or breakage. When lifting poles, a kevlar sling must be used whenever possible. Do not damage the ground stud which is usually located near the hand hole. Always follow these methods regarding loading and unloading of concrete poles.

Storage                                 Support so that poles do not bend. Unsupported length 4 ft +piling height. 8 poles maximum.

Transportation                    Support over entire length.

Moving on site

Poles up to 50 ft                   Pickup at two points 10

ft apart minimum.

Poles over 50 ft                    Support over entire length.

Loading or unloading

Poles up to 50 ft                   Use a one-point pickup at balance point.

Poles over 50 ft                    Use a two-point pickup with separation of at least 20% of pole length.

Erection

Poles up to 50 ft                   Use a one-point pickup above the point of balance and drag the butt into position.

Poles over 50 ft                    Use a pickup point which is 20 percent of the length from the top and is indicated by black tape around pole.

It is essential that digger derrick’s of suitable rating be used to lift concrete poles. In Table 2 the weights of concrete poles are listed. Compare these to the weights given for wood poles in Table 1.

Table 1

Additional Information for Wood Pole Specifications

Table 2

Concrete Poles Specifications

To determine how many wood poles the various pole trailers will carry and what lengths they will handle refer to table 3.

VEHICLE SETUP

           
For operation parking, the parking brake shall be applied on air
and hydraulic brake equipped trucks. In addition, on trucks with

hydraulic brakes, the micro lock is to be applied.

When operating on a slope wheel chocks shall be placed on the downhill side of two wheels. When operating on level ground, two wheel chocks shall be used, one placed in front and one behind a rear wheel.

For unattended parking, the vehicle parking brake shall be applied. The engine shall be switched off and the transmission placed in the lowest gear ratio. 

Whenever possible, the vehicle should be parked on level ground.

Wheel chocks shall be placed to prevent movement of a vehicle when it is unattended on sloping ground or adjacent to an excavation or a trench.

NOTE:            Don’t use “mico” brake lock (if vehicle has hydraulic brakes) for unattended parking, because pressure increase due to temperature change could damage the hydraulic brake system, or the vacuum lock could leak off leaving you without brakes.

Before leaving the cab do the following:

a)         Set the parking brake, and/or brake lock.

b)         Turn on flashing signals or warning lights, if necessary.

c)         To engage the Power take-off depress the clutch, and engage PTO

Set the outriggers before rotating the derrick. The outriggers shall be lowered firmly to the ground taking spring weight of vehicle leaving the tires in contact with the ground. A minimum of three outrigger pads under each outrigger on soft earth are required. However, to facilitate maximum outrigger extension, only one outrigger pads per outrigger should be used on hard surfaces

such as roads, pavement or rock, or to facilitate leveling on uneven ground if soil conditions permit.

GROUNDING VEHICLES

Refer to Pike Employee Handbook

Safety & Training Manual

410.1  PROCEDURE FOR GROUNDING MOBILE      EQUIPMENT

1.  When attaching grounds, employees shall pay close attention to make sure that all ground connections are secured tightly for continuity. (A ground is only as good as its weakest link!)

2.  When working in close proximity to energized circuits or circuits that may become energized, the metal parts of all line trucks, aerial lifts, mobile cranes, and trailers shall be grounded.

AERIAL LIFT GROUNDING EXCEPTION

When replacing street or area light bulbs or performing maintenance on street or area light fixtures from an aerial lift truck that has a fixed insulated section of fiberglass in the boom between the boom mount & boom tip, the aerial lift truck need not be grounded.

 


The following are considered good ground sources and should be utilized in the order listed below:

a)   The system (common) neutral located on the same level or above the energized conductor(s).

b) Pole grounds (if tapped to system neutral)

c)  Guy wires (if tapped to system neutral)

d) Substation equipment (if tapped to a grounding mat).

e) Transmission line tower ground footing.

A screw ground may only be used when a better ground source is not available (see a-e above) and approval has been given by the immediate supervisor or employee in charge.

3.  Running grounds shall be used in wire pulling operations when working in close proximity to energized circuits or circuits that may become energized.  The running ground and the wire pulling equipment shall be connected from the conductor being pulled to the system neutral prior to the operation of the wire pulling equipment.  (Any deviation from the above shall be approved by the immediate supervisor or employee in charge.  Penalty shall be imposed on the employee in charge at the location.)

4.  When operating a wire puller or tensioner in any area where the conductor being pulled could become energized, the puller or tensioner shall be isolated from other pieces of equipment by using an insulated rope, nylon sling, or other insulated material.

5.  Mobile equipment grounds shall be placed on the common neutral from the aerial bucket by using an approved live line shotgun stick.

Handling of Tools or Materials Item

211     CRANES, DERRICKS, HOISTING EQUIPMENT

A. The operator shall extend outriggers before operating cranes, derricks and/or other hoisting equipment (See Section 208).

B.  Only authorized persons shall be permitted in the cab or on the equipment.  Only those designated persons who are trained and qualified shall operate the hoisting equipment

C.  Prior to the daily use of cranes, derricks, and/or hoisting equipment, a visual inspection and operational check shall be made in accordance with the manufacturer or owner’s instructions.  If these instructions cannot be found, contact the Pike garage nearest you for a copy.

D.  Operating and maintenance procedures as specified by the manufacturer shall be followed.

E. The following are the minimum checks which shall be made daily prior to use:

1.   All control mechanisms

2.   All safety devices

3.  Deterioration or leakage in air or hydraulic systems

4.  Hooks, slings and load attachment devices

F. On the first lift of each day, the load shall be test-lifted (several inches) and the brakes checked.

G.  No person shall be permitted to ride the hook, sling or load of any hoisting equipment.

H.  It is extremely important that the operator familiarize himself with the following information prior to lifting with a crane, derrick, or any hoisting equipment:

1.   Approximate weight of object being lifted

2.   Capabilities of equipment doing the lifting

3.  Safe working load of the weakest link (rope, etc)(See Section 12 – Table 1)

I.  An operator of hoisting equipment should become familiar with the limits and capabilities of his equipment and exercise care to avoid overload.  A load should not be lifted with the derrick hoisting line that cannot be lifted by raising the load with the derrick itself.  Loads should not be dragged by rotating the derrick.  The lifting limits and capabilities of hoisting equipment can be determined by becoming familiar with the equipment load chart attached near the operator’s platform on the particular vehicle being operated. (See Section 12, Table 9 for example of how to read load charts.)

J.  All ropes, slings and other fittings shall be of sufficient strength, proper type and safe for their intended use. (See Section 12, Table 1)

K. No employee shall position himself under a suspended load or inside the angle of a winch line.

L.  Winch lines, ropes, or wire cables shall not be guided by hand when standing within reach of the drum or sheave.

M.  Poles shall not be pulled using the line truck derrick only.  A pole jack must be in conjunction with the derrick.  (Penalty to be imposed on the worker operating the equipment and also the foreman or other employee in charge if he is present.) An alternate method may be used only if no pole jack is available.  This alternate method is to dig a hole adjacent to the pole to be removed, pull the pole sideways to break it loose from the ground, and then remove it from the ground with the derrick.

N.  Operators of cranes, derricks, hoists and other hoisting equipment shall exercise extreme caution when in close proximity to energized lines or equipment.  When performing power transmission or distribution construction refer to Section 12, Table 2 for applicable clearance requirements.

O.  Vehicles equipped with derricks or booms shall be grounded before the derricks or booms are raised if there is a possibility that they could become energized.  The person in charge is responsible for grounding the vehicle.  The vehicle shall be grounded to the best possible source. (See 410.1(2)).

1005   ELECTRICAL HAZARDS ON THE GROUND

            The electrical hazard is not limited to people working aloft.  The groundman, or any other person working on the ground may also be exposed.  Listed below are several ways that an employee on the ground could be exposed to electrical contact.

1.  The “energized truck” caused by a contact between some parts of the truck itself (i.e. boom or aerial service device) and a conductor.

2.  The “energized tree” caused when contact is made between a tree and a conductor during a felling operation.

3.  An “energized wet rope” being handled on the ground when the upper portion contacts an energized conductor.

4.  An “energized fallen wire” brought down by accident.

5.  “Energized fences, guard rails or other conductive equipment” that may have become energized by fallen conductors.

All fallen wires, or wires hanging from pole structures shall be considered energized with potentially fatal voltages, unless they are known to be de-energized.

Any conductive structures in the vicinity, such as wire fences, guard rails, etc. shall be considered as energized and treated as such.

1006  DOWNED WIRES

IN THE EVENT ANY CREW OR EMPLOYEE ENCOUNTERS DOWNED WIRES, THEY SHALL:

1.  Barricade the area by any means available, including use of crew personnel as guards.

2.  Notify the power company.

3.  Notify the local police.

4.  Not touch or handle wires, except wit nonconductive tools, and then only when absolutely necessary to protect a life.

DIGGER DERRICK HAND SIGNALS
Whenever operating or working around a digger derrick or crane you should familiarize yourself with and use the proper hand signals.

With the noise around the work area the operator may not hear your instructions and could make a wrong move causing an accident. Refer to Figures 1, 2 & 3.

Figure 1

          

Figure 2 

        

                                                            Figure 3

AUGERING POLE HOLE
Before lowering or storing the auger when digging, make certain

that all operating personnel are in the clear and the boom is in a

position so that the auger will clear the truck body.

Familiarize yourself with the auger.

a)         Lowering the digger auger (Figure 4)

b)         Proper way of changing augers on digger derrick (Figure 5)

Figure 4 Hydraulic

Figure 5 Proper way of changing augers on digger derrick

After the auger has been lowered, position it over the stake location using the stinger extensions and rotation movement of the boom. Then set the point of the digger firmly on the ground. Using the auger, excavate a hole for the pole. The diameter and depth of the hold will depend on the pole size.

When starting to dig on inclines, angle the digger and auger to the point where the auger is at a right angle to the incline. Figure 6.

Turn the auger several revolutions before starting a gradual return of the digger to the vertical position.

An alternate method of digging on an incline is to level the site with a shovel prior to setting the auger.

Figure 6

Push the auger control to dig position and lower the auger into the ground by slowly lowering the boom. Control the rate of lowering the boom to get maximum penetration but try not to stall the digger which slows digging. When using carbide blades, always remove down pressure before reversing the auger to avoid damage to the carbide.

It is suggested that the auger be raised periodically and the soil be spun off during the digging. Soil can be spun off the auger flighting by allowing the auger to rotate at a moderate speed and using a shovel.

Keep the auger vertical by metering stinger extension and boom

rotation controls.

If digging is particularly hard, moving the stinger in and out, a foot or so on either side of the vertical position of the auger, will assist digging by concentrating the down pressure on one side, then the other alternately. Figure 7.

Figure 7

This method should be avoided when the auger has been extended to the end of the hexagon extension shaft. (Kelly bar).

If it is necessary to dig holes deeper than six or seven feet, move the auger to a lower attaching hold on the extension shaft. This shaft is 65 inches long and has several attaching holes which can be used to extend the auger. With the auger attached to the end hole, it is possible to dig holes deeper than eleven feet or to dig a seven foot hole over a four foot embankment.

POLE SETTING DEPTHS

The normal setting depth is measured from the ground on level

ground, Figure 8, and from the low point of the ground line on sloping ground, Figure 9.

               Figure 8                                      Figure 9

Wood poles should be set with the greatest curvature in the

direction of the line. They should be placed back to back with alternate poles facing in the same direction.

At angles and dead-ends the butt of the pole should offset away from the anchor, a distance not exceeding eighteen inches. The pole should be so set that after guy is attached and conductors are in place, the top of the pole will be in line with adjacent poles.

When back-filling a pole set in soil, should be tamped at 6-12 inch intervals. This is important if poles are to remain erect.

On steep slopes, near ditches or where the stability of the earth is suspected, it is advisable to check with customer for increased or decreased depth of setting of pole, Figure 10, in order to provide adequate pole footing strength.

Figure 10

The diameter of the hole to be dug shall be as small as is practical in order that maximum use is made of undisturbed earth to support the pole in the upright position. However, sufficient space must be left to permit the tamping bars to be used conveniently, effectively and down the full depth of the hole.

Pole Setting Depths

Recommended Pole-Setting Depths in Soil and Rock for Various Lengths of Wood Poles.

Length of                   Setting Depth           Setting depth

pole, ft                   in soil, ft                in rock, ft

25                                5.0                               3.5

30                                5.5                               3.5

35                                6.0                               4.0

40                                6.0                               4.0

45                                6.5                               4.5

50                                7.0                               4.5

55                                7.5                               5.0

60                                8.0                               5.0

65                                8.5                               6.0

70                                9.0                               6.0

75                                9.5                               6.0

80                                10.0                            6.5

85                                10.5                            7.0

90                                11.0                            7.5

95                                11.0                            7.5

100                             11.0                            7.5

105                             12.0                            8.0

110                             12.0                            8.0

115                             12.0                            8.0

120                             13.0                            8.5

125                             13.0                            8.5

130                             13.0                            8.5

135                             14.0                            9.0

HANDLING AND SETTING POLES

The Boom Tip Winch was developed especially for pole handling. Skill in the use of the Boom Tip Winch for handling and setting poles will enable the operator to handle poles quickly and safely and will result in considerable time saving.

Hook the winch line high on the pole above the balance point. The longer the pole, the closer the hook must be to balance point.

Before lifting the pole, lower the boom so that the Boom Tip Winch flanges are as close as possible to the pole. This will help keep the pole from swinging after the butt clears the ground.

When setting a pole in existing lines, raise the derrick into position first so that as the pole is raised by the winch line it can be guided readily into position between conductors, if possible.

Keep the winch positioned directly above the clevis while the pole is being raised. This will permit the winch line to wind evenly and will also prevent the pole butt from kicking out.

When the pole has been raised to the vertical position, pull up on the winch line until the pole is held firmly between the boom tip flanges and the pole claws to control the pole. You will now have complete control of the pole and can position it directly over the hole. If necessary, have a second crewman guide the pole butt into the hole.

As the pole is being lowered into the hole, it will be necessary to

retract the stinger slightly to maintain alignment as the boom is

lowered.

Note: Pike Electric, Inc. requires that once the pole hole is dug, before setting pole the bottom of hole must be tamped.

POLE SETTING PROCEDURE

The trainee is part of a crew assigned to dig pole holes and set poles, using an digger derrick and hydraulic tamper. The pole locations have been staked. The installations are in the vicinity of an existing de-energized line.

The trainees will alternate from operator to signal person allowing each participant to both install and direct the setting of a pole. Listed below are the duties of both the operator and the signal person.

Note:   The pole identification stamp is located either 10’ or 15’

from the pole butt, on the pole “face”, although this should

not be relied upon for pole setting depth.

POLE REMOVAL PROCEDURE

The trainee is part of a crew assigned to remove poles using a digger derrick and pole puller. The poles are ready to be removed, i.e., they are cleared of conductor, hardware and crossarms. The crew is at the work site. The poles to be removed are in the vicinity of an existing de-energized line. The roll of digger derrick operator and signal person will be alternated during the removal procedures.

POWER INSTALLED SCREW ANCHOR ( PISA)

One of the most common anchors you will use is the power installed screw anchor. To install it you use the digger derrick. The process is quite easy and takes only minutes,

There are two main items to keep in mind when using PISA. First, the anchor must be installed to a sufficient depth to provide a solid hold. Second, you must remember to set the anchor on an angle in the ground in line with the pull of the guy wire so it will hold the pole in place and won’t creep toward the pole by the stress on the pole. The observer is helpful in maintaining correct anchor angle.

Let’s look at the process you will use.

SETTING UP DIGGER DERRICK UNIT

During their installation, PISA can put excessive stresses on the digger derrick, especially at the turret end of the boom. You keep these stresses at a minimum when planning the digger derrick set-up. (Stand clear of unit while in motion),

In a two member crew, the operator watches the outriggers and screw anchor. The assistant watches overhead line clearance and the boom from the opposite side and directs the operator on required movements.

Set up the unit so the boom is in line with the screw anchor, if at all possible. This eliminates using rotation when installing the anchor, Figures 12 and 13.

Figure 12

Boom of digger derrick in Line With Screw Anchor

Figure 13

Boom of Digger Derrick in Line With Screw Anchor

Set up digger derrick as close as possible to installation site using brake lock, wheel chocks outriggers and planks.

Try to install the screw anchors from the turret side or back of the digger derrick. This allows better visibility when adjusting the position of the boom.

PREPARE ANCHOR WRENCH ASSEMBLY
Turn the auger in the ground so it will be self-supporting and remove the auger from the Kelly bar. A note about the auger holding bolt, it should be an SAE #5 grade bolt. This grade of bolt will snap off and pop out when it gets worn. A bolt of lesser strength will bend in the auger attaching hole and make bolt removal very difficult

Note:   An SAE #5 grade bolt has 3 marks on the head. An

unmarked bolt is a #2 grade.

INSTALL ANCHOR WRENCH ASSEMBLY
Install the combination Kelly bar adapter and locking dog assembly, (Figure 14a) to the Kelly bar of the digger. Insert the drive end assembly, (Figure 14b) into the locking dog assembly to complete the wrench assembly, (Figure 15).

                             Figure 14(a)                                     Figure 15 

CONNECT ANCHOR ROD TO WRENCH ASSEMBLY

Connect anchor rod to helix, Figure 16, and then slide rod into the drive end assembly. Make certain that the lower end of the drive end is engaged over the square portion or hub of the helix and ensure that the dogs are engaged under the hex collar at the top of the rod, Figure 17.

Note:   If more than one anchor is to be installed, the wrench can be left on the locking dog assembly. Care should be taken with this method when in the vicinity of energized apparatus; because of the extra height the wrench must be raised in order to accept the rod.

                  Figure 16                                Figure 17

INSTALLATION OF SCREW ANCHOR

Set engine RPM just high enough to turn the screw anchor. This

permits better control.

Take a good grip into the ground with the anchor in the near vertical position (Figure 18). This is especially important in hard or frozen ground. This prevents the anchor from walking along the ground.

Figure 18

If anchor will not start in frozen ground, start through frost with auger first.

Once the anchor is steady in the ground, retract/extend the stinger boom to the correct guy angle,

Figure 19

Start screwing the anchor into the ground while applying down pressure on the boom, at the same time operate the second stage boom extension to keep the Kelly bar and power anchor aligned (Figure

19).

Exert enough down pressure to keep the anchor from spinning

freely.

For every revolution of the screw anchor, the anchor should go into

the ground a distance equal to the pitch of the flighting.

If the screw anchor is at an angle to the boom, the assistant must

pay particular attention to the boom rotation. There are no indicator signs except the Kelly bar.

In order to prevent side strain to the rotating mechanism, it is a must to rotate the boom to follow the anchor into the ground.

Caution:         Excessive down force will bend the kelly bar and wrench.

Note:               With proper down pressure there is no need to float outriggers.

When installed incorrectly - not following anchor fast enough - the outrigger will be on the ground and the front end of the truck will tend to lift off the ground.

Following down with derrick and stinger boom, rotate the anchor slowly, which will pull itself into the ground. If the front end of the truck lifts or the Kelly bar bends, boom movements are required; stop anchor installation if necessary, to determine what boom movements are needed next.

The PISA must be installed to a minimum depth of 5 feet.  If soil conditions are poor, greater installation depths are required.

Note:   Figures 20 and 21 show correct/incorrect anchor
            installation angles and their resultant effects.

REMOVING ANCHOR ADAPTER

Remove any down or side pressure and release the locking dogs to the center position.

Remove anchor wrench at the appropriate angle to prevent the rod from bending. Install eye-nut on anchor rod.

Figure 20

Incorrect Anchor Angle

- Anchor will creep toward pole

- Pole will move in the direction of line tension

Figure 21

Correct Anchor Angle

- Anchor will not creep

In figure 22 is an example of practicing place a transformer on pads at different locations. Check with your foreman or operator for this type of exercise.

Figure 22

The purpose of this exercise is to familiarize you with digger derrick operation. It checks your understanding in the use of load charts, stability, vehicle set up and smooth operation of controls. The time spent now becoming familiar with the controls will prove to be valuable during the pole line construction module.

Another digger derrick exercise will be set up to install a power installed anchor as per the material you have just covered.