## 4 SmTS Scheme and Its Mechanical Characteristics Analysis
### Structural Design and Implementation of SmTS  
The SmTSs mentioned in [20; 30; 33] do not consider the uneven working condition of the roadway roof. Under this working condition, the temporary support cannot fully contact the roadway roof, so it is easy to have uneven stress in the support process. In order to achieve effective roof support, a kind of SmTS that can adapt to uneven roof conditions was designed based on the previous research, as shown in Figure 10. The equipment mainly includes a main beam, column, base, side guard board, four-bar mechanism, push jack, side guard board jack, and other mechanisms. This equipment adopts the form of two groups of support frames, which support each other and move forward alternately. Considering that the SmTS is subjected to a horizontal force during moving, a four-link mechanism has been installed between the equipment main beam and the base to prevent the equipment from tipping.  
The roadway section supported by the SmTS is rectangular. In order to prevent the roadway roof from falling, the top of the equipment bears the top pressure generated by the weight of the overlying rock, that is, the maximum wall rock pressure. The top pressure is the main factor of roadway damage. Taking the roof as the key support object of the SmTS, when the top pressure is transferred to both sides of the roadway, it causes the rocks on both sides to squeeze into the roadway. Both sides of the equipment bear the lateral wall rock pressure generated when the two sides of rocks are squeezed.  
The SmTS drives the roof beam and side shield through the column and side shield jack to provide a support force for the roadway roof and side wall formed by the new cutting, so as to prevent the roadway from large deformation, collapse, and other damage, reduce the disturbance to the roadway roof, and prepare for the subsequent permanent support.  
This kind of SmTS consists of two support groups at the front and back, which are connected by pushing jacks. The front and rear support groups support each other and move forward alternately. The pushing process is as follows:  
1. The piston rod of the side guard jack on both sides of the front support group shrinks, the side guard is separated from the coal wall, the column of the front support group drops, and the main beam is separated from the roof.
2. The rear support group is the support, the jack piston rod is pushed out, and the front support group pushes forward for one step. After the forward movement, the support is shown in Figure 11.
3. The column of the front support group rises, the main beam rises and supports the top plate, the side guard jack pistons on both sides of the front support group stretch  
Figure 10: Structural diagram of SmTS. 1. Main beam; 2. side guard plate; 3. side guard plate jack; 4. column; 5. base; 6. moving jack; 7. four-bar linkage.  
out, the side guard supports the coal wall, and the front support group completes the push frame.
4. The piston rod of the side guard jack on both sides of the rear support group shrinks, the side guard is separated from the coal wall, the rear support group column drops, and the main beam is separated from the roof.
5. The front support group is the support. The jack piston rod is pushed to retract, and the rear support group is pulled to move forward for one step. After the forward movement, the support is shown in Figure 12.
6. The column of the rear support group rises, the main beam rises and supports the top plate, the jack piston of the side guard plate of the rear support group stretches out, and the side guard plate supports the coal wall. A push cycle is completed.  
The SmTS can move forward in parallel with the roadheader. After the roadheader excavates the empty roof area, the SmTS can support the empty roof area in time to prevent the roof from falling, improve the roadheader startup rate, and improve the support efficiency.