## 2 Twin-Link Stepping Temporary Support Mechanism  
Introduction to the Complete Set of Equipment for the Excavation and Support Anchor System Based on Twin-Link Stepping Temporary Support  
The comprehensive set of excavation, support, and anchoring equipment, which is based on the twin-link stepping temporary support system, comprises a roadheader, multiple sets of twin-link stepping temporary support units, drilling and anchoring vehicle, bridge-type loading machines, belt conveyors, emulsion pumping stations, and other necessary equipment. The multiple sets of twin-link stepping units serve as temporary support for the working face of the excavation roadway. This equipment set is utilized to carry out various processes, including roadway excavation, temporary support, permanent support, and coal transportation. Figure 1 illustrates the layout arrangement of the complete equipment set, with the roadheader, temporary support brackets, drilling and anchoring vehicle, and loading machines arranged sequentially along the centerline. Figure 1: Diagram of the complete set of equipment for twin-link stepping temporary support. The twin-link multiple sets of stepping temporary support units consist of front and rear four-column hydraulic support units. These units include twin-link configurations, where two individual supports are connected as one group using shifting devices. The system also incorporates multiple sets of support units, allowing for the coverage of the temporary support area based on the required length of support. The stepping feature enables self-movement driven by hydraulic push-pull devices. Shifting cylinders connect the two hydraulic support units, enabling automatic shifting during the temporary support process. The twin-link multiple sets of stepping temporary support offer excellent stability and slip resistance, capable of fulfilling operational demands in roadways inclined up to 15 degrees. The design and structure of the twin-link stepping temporary support bracket are illustrated in Figure 2.  
The drilling and anchoring vehicle is a tracked construction vehicle with a double-row four-arm drilling system, as shown in Figure 3. The system consists of a mesh laying unit and a drilling and anchoring unit. The mesh laying unit is responsible for laying anchor nets on the exposed coal-rock surface in front of the temporary support units, forming a preliminary anchor support. The Principle of the Parallel Process for Exavation and Support Anchoring Based on the Twin-Link Stepping Temporary Support  
The construction unit establishes a temporary support zone at the face of the excavation roadway based on the twin-link stepping temporary support system. This innovation introduces a parallel operation process that encompasses excavation, temporary support, drilling, and anchoring. The primary objective of this process is to effectively utilize roadway space and streamline construction sequencing, resulting in reduced support sequence time and accelerated excavation progress. The parallel process operates as  
Figure 3: Diagram of the drilling and anchoring vehicle. Figure 2: Diagram of the structure of the twin-link stepping temporary support bracket. follows: the roadheader positioned at the forefront of the coal roadway performs slotting and section-cutting operations, while the twin-link stepping temporary support system advances with the roadway face to create a temporary support zone. The drilling and anchoring machine, located behind the temporary support zone, carries out permanent anchoring. The steps for implementing the parallel process of excavation, support, and anchoring are as follows:  
(1) Excavation and coal transportation by roadheader: Following the adjustment of the cantilever roadheader's position, the roadheader integrates the rotation of the cutting arm with the height rotation of the cutting head to efficiently perform coal cutting.