In the early days, people generally used multiple cranes and carriers to complete loading and unloading work.
With the continuous increase in loading and unloading operations, loading and unloading machinery that can pick up items by itself has gradually appeared.
At the beginning of the 19th century, single-bucket loaders appeared
In the mid-19th century, trackless loading and unloading machinery equipped with track skidding devices appeared.
Car tippers and crab rake loaders appeared in the 1920s
After World War II, container transportation has developed and container bridges and container gantry cranes have appeared one after another.
Forklifts are playing an increasingly important role in loading and unloading work
Despite this, cranes or conveyors are still used to complete loading and unloading work in some places where loading and unloading operations are not large.
From this point of view, it is very difficult to completely separate the loading and unloading machinery from the cranes, conveyors and handling vehicles.
Loading and unloading machinery can be divided into bulk material loading and unloading machinery and piece goods loading and unloading machinery according to the different materials to be loaded and unloaded.
According to the structure type, it can be divided into two types: fixed type and running type
The running type is divided into two types: track type and non-track type
Bulk material handling machinery Bulk material handling machinery is divided into vehicles and ships, including loaders, loading machines (ship), unloading machines (ship), bucket wheel stackers and reclaimers, etc.
Vehicle Bulk Material Loading and Unloading Machinery When loading, the full train of railway gondola cars generally use elevated silos or loading machines, and the non-integrated trains of rail vehicles and automobiles use single bucket loaders and bucket loaders. crab rake
When unloading the truck, in addition to the bottom opening vehicle, there are various methods of grabbing materials with a crane hanging bucket, unloading with a dumper, and unloading materials from the compartment with an unloader.
Many types of downloaders are used
Chain Bucket Unloader – straddles loading vehicle and moves on specially laid track
It is mainly composed of chain bucket elevator (see bucket elevator), belt conveyor, chain bucket lifting mechanism, complete vehicle operating mechanism, and metal frame composition (Figure 1).
The chain bucket grabs the material from the gondola and lifts it up, dumps it onto the bi-directional, horizontal conveyor and dumps it out of the chute
The chain bucket lifting mechanism is a set of drum pulleys, which can lift the chain bucket elevator
Chain bucket unloader operating capacity is generally less than 300 tons/hour
Its disadvantage is that there are often residual materials at the bottom of the vehicle and the dust flies when the vehicle is unloaded.
Screw unloader: The working device is a screw with two blades that rotate in opposite directions (Figure 2)
When the screw turns, the blade pushes the material out of the side door of the vehicle
The spiral can be raised and lowered to adapt to the height of the material
The operating capacity of the screw unloader can reach 1000 tons/hour, but it requires side-opening railway gondola cars, and the unloading section must have high causeways or tunnel yards.
In winter, if the bulk material freezes in the gondola, before using the above two unloaders to unload the material, it must be heated to thaw or break the frozen parts
Pneumatic Unloading Machine – Pneumatic conveying device used to unload bulk grain or cement loaded by box cars
Inertial truck unloader: The platform is supported by springs, and two rails with a certain height difference are placed on the platform (Figure 3)
After the car is pushed onto the platform, the body naturally leans to the side at a certain angle, and the coupler is automatically clamped
The motor drives the eccentric block installed under the platform to rotate
Due to the combined action of the centrifugal force of the eccentric block and the force of the platform support spring, the plane and the car vibrate longitudinally together (the amplitude is 40-70 mm, the frequency is 1
5-2 Hz), so that the volume materials in the car are discharged from the middle door
The working capacity per hour is 4-6 vehicles
Ship loading and unloading machinery for bulk materials The ship loader consisting of cantilevered conveyors is commonly used for loading at dedicated berths (Figure 4)
It can be moved along the shore track and the cantilever can be tilted and retracted to accommodate changes in hatch width and water level
There is an enclosed telescoping barrel at the discharge end of the conveyor to reduce dust from bulk materials.
To make the bulk material fill the corner of the cabin, a turning mechanism is provided to make the barrel swing in any vertical plane, or a rotating belt launcher is installed at the lower end of the barrel
When loading the ship, the bulk materials are shipped from the shipyard and transferred to the main boom conveyor through shore belt conveyor, and then loaded into the ship through cantilever belt conveyor and material barrel.
Its operational capacity can reach 20
000 tons / hour
There are many types of ship unloaders and the working devices work continuously
Ship unloader with chain buckets: the chain bucket is raised after taking the material out of the cabin and the bulk material is transported by the conveyor belt (Figure 5)
It is mainly used for open barge unloading and its energy consumption is lower than that of bucket unloading.
The chain bucket structure has two types: rigid suspension and flexible suspension
The first is rigidly inserted into the stack to retrieve the material; the second is based on the free-hanging chain bucket and the chain to dig the material, which can adapt to the shock of the hull, avoid the collision between the bucket and the bilge, and has a better clearance effect
The operating capacity can reach 6000 tons/hour
Rope Bucket Ship Unloader – Replace Flexible Hanging Chain With Steel Cable
It has light weight and high working speed
Bucket Wheel Ship Unloader: It is made by adding 1 or 2 bucket wheels to reclaim chain bucket ship unloader
The bucket wheel and bucket chain lift and rotate together, the discharge effect is good, and there are almost no dead corners in the cabin.
Vertical screw ship unloader: Equipped with closed vertical screw and rotation, pitch, roll and other mechanisms
The vertical screw is driven by electric motor or hydraulic motor, and the lower end of the screw shaft has a guide wing plate for feeding.
The operating capacity is from 100 to 1200 tons / hour
Pneumatic ship unloader – a pneumatic conveying device used for unloading ships, commonly used to unload bulk grain and cement
The suction nozzle can reach every corner of the cabin and can clear the cabin by itself
The disadvantage is high power consumption and noise
The operating capacity can reach 1000 tons/hour
Loaders are often used for equipment other than vehicles and ships to complete bulk material loading work
Machinery parts for loading and unloading goods are used for bagged, packed, bundled, boxed and lumber, metal profiles, machinery and equipment and other finished items.
Various cranes and lifting vehicles equipped with the corresponding picking devices are generally used
The loading and unloading machinery used for containers and pallets are mainly container bridges, container gantry cranes, straddle carriers, forklift trucks and pallet jacks.