We have a weight on the piston, and that weight is chosen so that p2 it acts as though p external is equal to p2.(让活塞上放一重物，让它的效果刚好,等同于外压强。)
You may think of it as the free running piston in your vehicle's engine.(你可能会认为它当作免费的运行活塞在您的汽车的引擎。)
We've got my container, my piston here.(这里是容器和活塞。)
The final step came when steam was introduced into the cylinder to drive the piston backward as well as forward, thereby increasing the speed of the engine and cutting its fuel consumption.(最后一步是将蒸汽引入气缸，使得活塞前后推动，从而提高了发动机的速度，降低了燃料消耗。)
So I've got, this piston here is compressed, and I slowly, slowly increase the volume, drop the temperature.(这样，这个活塞就被压缩了，然后我再很慢很慢地增加它的体积，降低温度。)
A piston engine is said at best to be only 33% efficient.(一台活塞式发动机被充其量说只成为有效率33%。)
Each piston disassembled and polished, each nut and washer cleaned or replaced, accounted for.(每个活塞都要拆下来并且打磨，每个螺母和垫圈都要清洗或更换，并且一个都不能少。)
Replace piston rod and add flow passage on piston rod.(更换活塞杆，在活塞杆上增设流道。)
Filling the cylinder with steam pushes the piston out.(填充汽缸的蒸汽将活塞推出。)
And the total pressure is given by the piston here.(总的压强由，活塞给出。)
