AL PÚBLICO GENERAL
4. COMPORTAMIENTOS Rutinas cotidianas, o no tanto
13.4.1 Rated Capacity of Other Mobile Plant
The rated capacity of other mobile plant is the maximum mass that maybe handled at the maximum lift point radius, or reach, for each lift point, without the strength and stability requirements being exceeded. When determining the allowable load to be lifted, the mass of any attachments, such as buckets or quick hitch, must be deducted, unless the rated capacity chart allows otherwise. To ensure the stability of the mobile plant, the rated capacity of the plant must not be greater than:
1. 75 % of tipping load in the stationary mode; 2. 66% of tipping load in the pick-and-carry mode; or
3. 50% of tipping for articulated wheel loaders and tool carriers.
13.4.2 Load chart
The load chart for the mobile plant must identify each lift point location, and the corresponding rated capacity for each position. The appropriate load chart must be fixed inside the operator’s cab and show the following information:
1. Manufacturer’s name and model;
2. Boom and dipper arm identification and length, particularly where different boom configurations maybe used;
3. Track width, where this is variable;
4. Deductions for attachments, such as bucket or quick-hitch devices, so that the information on the requirements for earthmoving equipment. net allowable load to be lifted can be determined by one of the following:
i. the rated load at the least stable position; or
ii. where variable load rating is provided for, means to clearly determine the load position in accordance with the rated capacity chart.
13.4.3 Lifting Points On Earthmoving Plant
Lifting attachments on earthmoving plant are sometimes supplied by the plant manufacturer. If this is not the case, the attachments must be designed by an engineer. Lifting attachments often consist of a welded assembly that fits onto the end of the dipper arm when the bucket is removed. All lifting points on earthmoving plant must form a closed eye, to which a load rated shackle maybe attached.
(WARNING: Quick couplers or hitches shall have independent latching devices)
Typical example of a quick coupler or hitch boom and bucket
As a rule, excavators are less suitable than most common types of cranes for precision lifting and placement applications. Precision lifting and placement requires the plant to operate at creep speed (inching), and to support the load without drift while connections are being made.
The inherent 'hydraulic drift' characteristics, and the absence of an integral winch and hoisting rope, rules out the use of excavator for precision lifting and placement.
The erection of structural steel and multi-crane lifting (dual lifts) are applications where the use of excavators are not suitable and must not be used, mobile cranes shall be used.
The loads to be lifted, the weight of the loads and the load radius are in compliance with the instructions, information or restrictions provided by the manufacturer of the excavator.
1. Ensure that the maintenance records are available with the earthmoving equipment. 2. Make sure a logbook, containing daily check sheets, prepared either by the manufacturer,
supplier or a competent person, accompanies the earthmoving equipment.
3. Make sure that plant inspection and maintenance is within the date specified by the maintenance manual and check sheets. (Inspection and maintenance is usually dependant on environmental operating conditions).
4. Check that a manufactures load chart is mounted inside the operator's cabin. The load chart shall include the following information:
a. The manufacturer's name; b. Date of manufacture;
c. Plant model identification and serial number;
d. The location of lifting points, and their corresponding rated capacity, and
e. The rated capacity or working load limit (WLL) of the plant corresponding to the position of each lifting point, and boom configuration.
5. Check that the working load limit (WLL) is marked on the boom of the machine. This is important because booms on earthmoving equipment are sometimes interchanged and capacities may vary. (Note: The WLL is equal to the sum of the weight of the lifted load and the lifting attachments. In order to determine the weight of the freely suspended load, the weight of the lifting attachments must be deducted from the WLL).
6. Make sure that each lifting point forms a closed eye. Lifting points maybe a lug located on the boom, arm, bucket or linkage, or a quick coupler or hitch frame as specified and rated by the manufacturer.
7. Check to ensure that lifting slings cannot become detached from the lifting point or load, and that slings will hang clear of the boom, or boom attachment.
13.4.4 Quick Coupler or Hitch
Loads shall not be suspended from a lift point fitted to a bucket or attachment coupled to the boom via a quick coupler or hitch unless the quick coupler or hitch is secured by an additional independent latching device which:
1. Is positively and mechanically locked in an engaged position, and 2. Must be intentionally disengaged for the attachment to be uncoupled.
Quick coupler or hitch shall only be used to support attachments for which they have been specifically designed. Quick coupler or hitch must be maintained in proper working order and shall be marked with the model and serial number, manufacturer's name, quick coupler or hitch weight, and maximum rated capacity, as well as the capacity of each lifting point.
13.4.5 Working Practices
Whenever earthmoving equipment is used in a crane configuration, its operation shall be consistent with the advice provided in the manufacturer's manual and with the following rules:
1. Make sure the machine is only travelled with its arm and boom retracted to minimum practicable radius.
2. Where the machine requires the use of stabilisers in order to achieve stability, make sure they are always used.
3. Make sure loads are not suspended from bucket teeth or adaptors. 4. Make sure no person is ever permitted under the boom or suspended load. 5. Never permit a person to be lifted by earthmoving equipment.
6. Make sure lift points are arranged so that accidental unhooking of the load cannot occur. 7. Where the sling or lifting tackle is wrapped over the back of the bucket, make sure it
cannot come into contact with any sharp projection or sharp edge.
8. Make sure deductions from the rated capacity for larger than standard buckets or quick coupler or hitch devices have been made to determine the maximum allowable weight of the load to be lifted.
9. Make sure operational speed is reduced from high-speed excavator mode where possible. 10. The excavator must not be used for lifting operations if working on a gradient.
13.4.6 Other Precautions:
1. Movement alarm and flashing beacon must be fitted.
2. Convex mirrors to allow vision from the drivers seat (without slewing) at all points 1 metre high and 1 metre from the machine
3. Ensure a suitable clearance for ‘tail swing’ behind and around the machine – danger area shall be barricaded.
4. A banksman must be in attendance during lifting operations.
5. Communications with the driver/operator must be established, i.e. signals, radio, etc. 6. Bucket or load shall not be slewed directly over personnel.
7. Vehicles shall be loaded from the side or rear and material shall not be dropped from excessive height.
8. Dangerous overhangs must not be created on a high workface and a workface below a machine shall not be undercut so as to affect machine stability.
9. Wheels or tracks shall be placed at 90º to the workface. 10. Soil type shall be taken into account when positioning vehicle.
11. If working on a gradient, the maximum gradient shall be as specified by the manufacturer, the working cycle shall be slowed down, the bucket shall not be extended too far in the downward direction.
12. Drivers’ cabin shall be suitable to protect from adverse weather conditions at all times. 13. When travelling, the bucket shall be tucked into the machine and clear of the ground. 14. Avoid contact with overhead lines and underground utilities.
16. Excavators must not be used to "pick and carry" loads (i.e. travelling with a suspended load).