T012202E
Telescoping the Boom [NOTICE] ◆ The extended boom retracts, though slightly, in course of time, due to hydraulic oil temperature change. For example, 15 ft (5 m) extended boom retract by approx. 1.6 in (40 mm) along with lowering of temperature by 50°F (10°C). Besides temperature, the boom’s telescoping conditions, boom angle, lubrication, etc. affect the amount of retraction. For boom retraction prevention, use the following precautions: • Do not extend the boom when the hydraulic oil is extremely high. • Manipulate the telescoping control lever slightly to the EXTEND direction to mitigate the oil effect. • Fully extend the 2nd boom section for working with this section.
Controls 4
5
3
2 1
T21631
1. Boom telescoping control pedal 2. 2nd boom emergency telescoping switch 3. 3rd/top boom emergency telescoping switch 4. 3rd/top boom extending switch 5. Boom telescoping control lever
The boom consists of four sections. The telescoping of these boom sections is controlled by using the boom telescoping control lever, the boom telescoping control pedal and the 3rd/top boom extending switch. The telescoping speed can be controlled by changing the amount the boom telescoping control lever and the boom telescoping control pedal are moved and by using the accelerator pedal. To extend: Push the lever forward. To retract: Pull the lever rearward. To stop: Return the lever to neutral position.
Extending and Retracting the Boom WARNING Moving the control levers abruptly is dangerous because it causes the load to bounce and swing. Operate levers slowly and carefully. When the boom is extended, the load radius increases. Be alert to any sign of overloading when extending the boom. A boom telescoped incorrectly can collapse if a lift is made in this condition. Watch out for any error in the boom section telescoping sequence while operating the crane. Do not push or pull the load by telescoping the boom. This practice can damage the crane and lead to an accident.
Telescoping the Boom
Push（to extend）
Boom telescoping control lever
Neutral(stop)
Pull（to retract）
3rd／top boom extending switch T20917E
96
Telescoping the Boom
