Bucket loader

Bucket loader - earth moving machine intended mainly for loading and transportation of excavated material to the close distance, using a bucket with a much larger capacity than an excavator bucket. Loaders work above the ground level and the bucked is filling by the drive mechanism. Loaders are machines working in intermittent cycle. They are mainly used in the mining and construction industry.

History

History of bucked loader started in the 20s of the twentieth century. Then began to mount outriggers on tractors with rotary scoop with low capacity. The whole mechanism was lifted by ropes and winch driven by the tractor's engine, bucket was emptied by gravity. The rapid development of loaders took place in the years 1944-1947, when the Frank G. Hough introduced hydraulics system to his vehicle and engine mounted on the rear frame. In the 50s and 60s was introduced four-wheel drive, whose bridges combined articulated frame. These elements, as standard in the construction loaders, survived to the present day, have changed only the materials and technologies.

Classification

Bucket loaders are available in many varieties. Criterion of classification:

• Construction of the chassis:

- Tracked loaders

- Wheel loaders with articulated or rigid frame

• Assignment:

- Ground,

- Mining,

• Way of working:

- Frontal

- Rotary

- With a bucket pivoted to the side,

- The landing overhead,

• Working capacity of the bucket:

- Light (bucket capacity of 0.5 m3 to 2.0 m3),

- Medium (bucket capacity of 2.0 m3 to 5.0 m3),

- Severe (bucket capacity of 5.0 m3 to 10.0 m3),

- Very heavy (capacity greater than 10.0 m3).

Structure

Construction of loaders consists of two basic units: drive system for moving machines and operating system.

The drive system (for wheel loaders) consists of such elements as:

- Diesel engine

- Torque converter

- Gearbox,

- Drive shafts,

- Drivetrain,

- Hub reduction gear,

- Wheels.

The elements of the working system include boom and bucket vessel. Operating system can be divided into two types: type "Z" (used in the majority of loaders) and the type of "parallel" (senior structurally and reaching less pulling force).

Boom with lifting mechanism:

- Ternary lifting system and ternary bucket system,

- Ternary lifting system and four-membered bucket system,

- Four-membered lifting system with parallelogram - allows to keep constant angle of the bucket to the specified level for different boom position.

In standard loader is equipped with a front-mounted square wide bucket connected to the end of two booms (arms). But it can be replaced with other additional equipment which increase the functionality of the machine and form it more universal. Such additional accessories may be: - Special buckets eg. for light material (characterized by large capacities), buckets for stones, multifunctional Drott’s bucket (ie. 4-in-1 - to: loading, pushing, grabbing, leveling ground)

- Hydraulic gripper,

- Forks,

- Hydraulic shears,

- Snow cutter,

- And others that can be fitted with a universal joint.

Principle of working

Loaders are working in intermittent cycle. The cycle consists of a loading process, which includes: shift loader bucket to the windrow of excavated material (walls, floors), delving bucket (while driving the machine), filling the bucket during its rotation, lifting boom, drive the machine to the point of unloading, emptying buckets and return to the place of loading.

The loading process can be divided into four main steps:

1. Drive,

2. Filling,

3. Lifting (lowering)

4. Unloading.

The total time (Tc) cycle working of loader is the sum of the partial times, namely:

Tc=t1+t2+t3+t4+t5+t6+t7+t8+t9

t1 – time of filling the bucket,

t2 - time of lifting buckets to transport position with the time of withdrawal the machine,

t3 - driving time loader to the means of transport,

t4 – time of lifting and shift buckets to excavated material,

t5 – time of emptying the bucket,

t6 – time of lowering buckets to transport position and withdrawal the machine,

t7 – time of driving back,

t8 – time of lowering and shift buckets to fill it

t9 - the total time needed for switch the lever at the individual movements, depends on the construction of the loader and the operator’s skills.

Bibliografia

Marek A. Stańkowski, STALOWE KOLOSY, LIBRA, Rzeszów 2010, ISBN 978-83-89173-60-6

Artur Bęben, MASZYNY I URZĄDZENIA DO WYDOBYWANIA KOPALIN POSPOLITYCH BEZ UŻYCIA MATERIAŁÓW WYBUCHOWYCH, AGH, Kraków 2008, ISBN 978-83-7464-157-9

Kazimierz Pieczonka, ŁADOWARKI ŁYŻKOWE, Wrocław 1971