What is a forklift mast? Forklift mast design
Mast system structure
1.1 Forks
1. Fork structure
2. The fork is the most basic and common lifting device on a forklift. Forklifts are generally equipped with two identical forks.
3. The fork is mounted on the forklift. It is an L-shaped member consisting of a horizontal section and a vertical section. Typically, the horizontal and vertical sections of a fork are integrally formed, known as a one-piece fork. Some small-tonnage forklifts have separate horizontal and vertical sections connected by a pin, allowing the horizontal section to lie flat or fold upward, aligning with the vertical section. This is called a folding fork. This design uses an integral fork.
4. When the forklift is picking up cargo, the horizontal section of the fork is inserted into the bottom of the cargo or pallet. Once lifted, it is used to carry the cargo. Therefore, the upper surface of the horizontal section of the train must be flat, with a slightly angled lower surface at the front end. This allows the forks to be thinner and gradually taper to a narrower front end, with rounded edges on either side. This facilitates fork insertion and removal of cargo. The vertical section of the fork connects to the fork frame, and is categorized as either hook-type or cross-type, depending on the connection method. To position the forks on the fork frame, a locating pin is installed on the upper hook. This locating pin inserts into a groove in the fork frame's upper crossbeam to prevent the forks from moving freely. When the locating pin is lifted upward, the spring force is overcome, and the pin shaft disengages the groove in the fork frame's upper crossbeam, allowing the forks to be moved and the spacing between them to be changed.
1.2 Fork Carriage: The fork carriage, also known as the carriage, is used to mount forks or other tools and attachments and to lift and lower cargo.
Depending on the fork carriage's position within the gantry system, the weight of the cargo is transmitted to the lifting chain by the fork carriage. The torque generated by the cargo weight is then transmitted to the gantry through the fork carriage. As the chain drives the fork carriage up and down, the fork carriage must reliably follow the gantry rails. This dictates that the forklift is a vertically moving trolley, generally consisting of two parts. The front section is a welded frame structure, primarily used to mount the forks and other attachments. The rear section consists of two rows of roller frames equipped with guide rollers, welded to the front section and integrally formed. They are pulled by chains and raised and lowered vertically along the mast rails. Forklifts come in two types: plate-type and slide-bar-type, depending on the type of fork and how it is mounted on the frame. This design uses a plate-type forklift.
A plate-type forklift is used when the fork is a hook-type. Plate-type forklift frames come in various configurations, but are generally constructed from welded steel plates or cut from a single piece of steel to the desired structure, with excess material removed to reduce weight. The upper hook of the fork is attached to the upper crossbar of the frame, while the lower hook is attached to the lower crossbar. Since the mounting dimensions of the hooks and the rack are standardized, all attachments have the same hooks as the forks. Plate-type forklifts facilitate attachment replacement, making welded plate-type structures widely used.
Forks and other attachments can be installed and removed from the side of the fork frame. When a cargo backstop is installed on the fork frame, side installation and removal are inconvenient. A notch is provided in the center of the lower crossbeam of the fork frame to facilitate installation and removal of the forks. To position the forks and other attachments on the fork frame, several symmetrical positioning holes or slots are provided on the upper crossbeam of the frame. Spring-loaded positioning pins are installed on the hooks at the upper ends of the forks. The forks can be slid on the fork frame to adjust the spacing between the forks and position them appropriately according to the size of the cargo.
The rollers on the fork frame transmit the weight of the cargo to the mast in the form of a torque. Because the rollers are spaced at a fixed distance, they exert a significant force on the mast uprights and should be arranged appropriately. The lateral rollers absorb the lateral forces of the fork frame. Lateral forces can be generated by misaligned cargo placement on the forks or when operating on a sloped surface. To prevent the forks from interfering with the mast's normal movement, lateral rollers are essential. Neutral rollers can also be used to increase the spacing between the lateral rollers.
1.3 Inner and Outer Door Frames The inner and outer door frames are portal frames consisting of two left and right columns respectively, connected by different numbers of cross beams at the top, middle and bottom. The columns are both the main load-bearing components of the door frame and the guide rails for the fork frame or inner door frame to move up and down. The cross-sections of the columns are trough-shaped, I-shaped and other special-shaped, and the materials are mostly low-alloy steel. The left and right columns are connected by two to three cross beams to form a frame structure, which are then nested together. Relying on the rollers installed on the inner and outer door frames, the inner and outer door frames roll along the outer door frame columns. When steel sections with different cross-sections are used as door frame columns, there will be a variety of parallel combinations of inner and outer door frame columns. This design adopts the frame structure of the CL-type inner and outer door frames.
