What are crossing spans steps for walking type launching girder?

Basic crossing spans steps for walking type launching girders are as follows:

1. Hydraulic cylinders in the front support leg and rear bracket jack up the main girder to a certain height, and drive in pins to inner and outer sleeves. Then middle support leg moves forward along the main girder about 30m depending on its own hanging mechanisms. Then put down middle support leg and transverse sliding rails and firm them;
2. Drive out pins, then the complete machine falls down, make front trolley and rear trolley move forward near to the middle support leg, start roller mechanism of middle support leg and rear bracket to make main girder move forward 10m, at the same time two trolleys move back about 10m;
3. Hydraulic cylinder in the rear support leg jacks up the main girder to proper height, cylinder in the rear bracket draws back to make it suspend, then rear bracket moves forward (by manpower)along the main girder 15m to the proper position, then level it and drive in pins; and then hydraulic cylinder in the rear support leg draws back to make it suspend;
4. Start roller mechanisms of middle support leg and rear bracket to make main girder move forward 10m;
5. Front trolley and rear trolley move at the same time backward to the rear part of main girder, the front trolley lifts one end of pre-cast girder as counterpart when girder carrier carries the pre-cast girder to the right position, connect them firmly;
6. Start roller mechanisms of middle support leg and rear bracket to make main girder move forward 10m, then the front support leg reaches the right position and stands up on the pier. Check all mechanisms to prepare for girder installation