Gravity shelves, also known as self-gravity shelves, belong to heavy shelves. They are evolved from pallet shelves. They are suitable for the storage of a small number of similar goods in large quantities. The space utilization rate is very high. The depth and number of layers of gravity shelves can be determined according to needs. Gravity shelf is one of the derivatives of cross-beam shelf. The structure of the shelf is similar to that of cross-beam shelf, but the roller track is installed on the cross-beam, and the track is inclined to 3-5 degrees. Gravity rack, also known as roller rack rack, belongs to pallet storage rack in storage rack. The pallet goods are transported to the shelf entrance by forklift truck. With self-weight, the pallet glides automatically from the entrance to the other end of the intake port. Gravity shelves belong to the first-in-first-out storage mode.

1. Working Principle of Gravity Shelf
Gravity rack is also called roller rack.
The utility model belongs to a pallet storage shelf in a warehousing shelf. Gravity shelf is one of the derivatives of cross-beam shelf. The structure of the shelf is similar to that of cross-beam shelf, but the roller track is installed on the cross-beam, and the track is inclined to 3-5 degrees. The pallet goods are transported to the shelf entrance by forklift truck. With self-weight, the pallet glides automatically from the entrance to the other end of the intake port. Gravity shelves belong to the first-in-first-out storage mode.

Gravity Shelf Introduction:
Gravity shelf, known as mobile shelf, is a storage system that uses the gravity of the stored goods to achieve the movement of goods in the direction of storage depth.  Most of them are used in picking system, which is a widely used equipment in modern logistics system.
Gravity shelves and general shelves are similar from the front, but their depths are much deeper than those of general shelves, similar to many shelves leaning densely.  Often used in conjunction with flow devices and rollers, each layer of diaphragm is low at the front end (delivery end) and high at the back end (import end). So that the cargo body can move from high to low by using the self-weight of the cargo body on the channel with a certain height difference, thus completing the operation of stocking, storing and discharging from the warehouse.
The main characteristic of gravity shelf is large storage capacity per unit warehouse area. Gravity shelf is a kind of intensive shelf, which can store goods intensively on a large scale, thus reducing the number of passages and effectively saving the area of warehouse. The area of warehouse can be saved by nearly 50% after changing from ordinary shelf to gravity shelf.
There are two main applications of gravity shelves: one is that large gravity shelves have large storage capacity and can be stored in large quantities. The other is that light and small gravity shelves are widely used as picking shelves in distribution centers, transshipment centers, warehouses and stores. It can also be used in parts supply line of production line.

2. Characteristic of Gravity Shelf
1. Goods are stored at the high end, slipped to the low end and removed from the low end. In the course of cargo sliding, dampers are installed on the sliding track to control the speed of cargo sliding within the safe range. A separator is arranged at one end of the slideway, and the cargo at the first board position can be removed smoothly by the handling machinery.
2. Goods follow the FIFO sequence. The shelf has high storage density and flexible coordination function.
3. Suitable for pallet-based storage operations, neat cargo stack, which provides a better solution for the storage of heavy goods. The utilization rate of storage space is more than 75%, and only one access is needed.
4. Gravity shelves are very environmentally friendly. They are all powerless, energy-free, low noise, safe and reliable, and can operate at full load.
There is no working channel between groups of shelves, which increases the space utilization rate by 60% and improves the storage volume ratio; tray operation follows the principle of first-in-first-out; automatic storage and rotation; the separation of storage and picking greatly improves the output, because self-gravity makes goods slide and there is no operating channel, so the number of transportation routes and forklift trucks is reduced.

3. Notices for Gravity Shelf
The total shelf depth (that is, the length of the guide rail) should not be too large, otherwise the unusable upper and lower "dead angle" will be larger, affecting the space utilization, and the slope is too long, the controllability of the slide will be poor, the impact of the slide will be greater, easy to cause the slide is not smooth, blocked, pallet cargo overturning. In order to make the descent smooth, if the ramp is longer, a damper should be installed in the middle to make the pallet cargo.
It is difficult to design, manufacture and install the buffer device and cargo separation device at the lowest part of the ramp without overturning due to excessive impact when sliding to the lowest end. Such shelves should not be too high, generally within 6 meters, the weight of single cargo is generally less than 1000KG, otherwise its reliability and operability will be reduced.