A telehandler, or telescopic handler, is a construction machine that combines the lifting ability of a forklift with the reach of a crane-like boom. Its telescoping boom can extend upward and forward to place palletized materials on roofs, scaffolds, or upper floors. This makes the machine valuable on job sites where loads must move both vertically and horizontally.
The key physics idea is that reach changes leverage, so the same load can be safe close to the machine but unsafe farther away.
Key Facts
- Load moment = load weight × horizontal distance from the front axle.
- As boom length increases, the maximum safe load decreases because the tipping moment increases.
- A load chart gives the safe lifting capacity for each boom angle, boom extension, and load position.
- Stable lift condition: counterweight moment must be greater than load moment, with a safety margin.
- Hydraulic pressure creates lifting force: F = P × A, where P is fluid pressure and A is piston area.
- Center of gravity must stay inside the machine's support base to avoid tipping.
Vocabulary
- Telehandler
- A construction vehicle with a telescoping boom used to lift and place loads at height or at a distance.
- Telescoping boom
- An extendable arm made of nested sections that slide out to increase reach.
- Load chart
- A safety table or diagram that shows the maximum load allowed for different boom angles, extensions, and distances.
- Load moment
- The turning effect produced by a load, equal to the load weight multiplied by its horizontal distance from the pivot or axle.
- Hydraulic cylinder
- A device that uses pressurized fluid to create a strong linear force for lifting or moving machine parts.
Common Mistakes to Avoid
- Using forklift capacity as telehandler capacity is wrong because a telehandler's safe load changes with boom reach and angle.
- Ignoring the load chart is unsafe because a small increase in forward reach can greatly increase the tipping moment.
- Assuming a level lift on uneven ground is wrong because slopes shift the center of gravity and reduce stability.
- Lifting with the load far from the fork backrest is incorrect because it increases the effective distance and lowers the safe capacity.
Practice Questions
- 1 A telehandler lifts a 1200 kg pallet whose center is 2.5 m in front of the front axle. Using g = 9.8 m/s^2, calculate the load moment in N m.
- 2 A load chart allows 3000 kg at a 2.0 m reach and 1500 kg at a 4.0 m reach. A 1800 kg load must be placed at a 4.0 m reach. Is this lift within the chart limit, and by how much is it over or under?
- 3 Explain why extending the boom forward can make a telehandler less stable even if the load weight does not change.