In the Northern Song Dynasty, apart from the general crossbow, the infantry's long-range weapon further developed a heavy-duty long-range weapon, namely the bed crossbow with compound bow.
Bed crossbow, also known as bed crossbow, was developed on the basis of winch crossbow in Tang Dynasty. It is a combination of two or three bows, which greatly enhances the tension and strength of the crossbow. When the crossbow is stretched, the crossbow string is connected to the winch with thick rope. The soldiers turned the winch, pulled open the crossbow string and loaded the giant arrow. When radiating, the soldier should use a sledgehammer to jerk the trigger and shoot the arrow into the distance. There are eight kinds of bed crossbows with compound bows recorded in General Theory of Martial Arts, which can be divided into two types according to the strength and range of crossbows. One is a double bow bed crossbow, equipped with two bows, which are placed in front of and behind the thick crossbow arm. When launching, first use a thick rope with hooks at both ends, one end hooks the crossbow string, and the other end hooks the shaft of the winch. Then use five, seven or more soldiers to twist the winch together, open the crossbow string, and buckle it on the machine teeth, so as to ensure that the crossbowman who is loading an arrow is properly equipped with the crossbow and aimed at the target. When radiating, you can't pull the trigger with the strength of human hands. The archer in charge of launching must hold the sledgehammer high and hammer the trigger with all his strength, so that the huge crossbow will roar and fly to the enemy. These arrows are very thick and have a flat chisel shape, so they are called "chisel arrows" with a range of about 120 to 135 steps.
The other is a three-bow bed crossbow, which is more powerful than the former and doubles its range. The three crossbows on the crossbow arm, two at the front end and one at the back end, are also relatively installed. Because this kind of bed crossbow is more powerful, it is also called "eight cows crossbow", which means that only eight old cows can open it. Generally, it takes 20 to 100 people to open the crossbow by manpower, and the general range is 200 to 300 steps, which is about 370 to 560 meters. The crossbow used in the three-bow bed crossbow is bigger, the shaft is thick and the arrow feather is iron. The front end is equipped with a huge iron arrow with a triangular blade. Because its size is similar to the pike used by ordinary soldiers, it is also called "one gun, three swords and arrows" It also has another name called "Treading Arrow", because it also has a special function, that is, when attacking an enemy castle, it shoots a thick three-bow crossbow arrow at the enemy wall, so that the front end of the crossbow arrow is deeply inserted into the wall, leaving only half of the thick shaft and tail feather exposed outside the wall. Under their own cover, siege soldiers can climb the city wall with these huge arrow shafts inserted in the wall and capture the city. As a result, this huge crossbow arrow became a stepping stone for siege climbers to climb, so these arrows were called "stepping arrows".