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Spare the rod, double the stroke
The continuing trend to make machines smaller by taking advantage of more compact components is the driving force behind the increasingly widespread use of rodless cylinders. The three main types of rodless cylinders are the piston-lug version, the cable cylinder, and the flexible-wall cylinder. Most of these are designed for use with pneumatics, but some manufacturers provide ratings for low-pressure hydraulic service.
The piston-lug design works in a fashion similar to that of a conventional cylinder, but does not move the load through a rod. Instead, a bolt extends from the side of the piston out through a longitudinal slot in the barrel. A drive lug is attached to the end of the bolt and moves directly with the piston.
To seal the slot between the piston and lug, steel bands pressing against each other separate when the bolt passes by. Different piston widths are available to meet any bending moments imposed by a load. Stroke lengths of piston-lug cylinders can exceed 30 ft. Options include position switches, brakes, and carriages to support loads and maintain alignment.
A variation of the piston-lug cylinder uses a permanent magnet in the piston to create a magnetic field that links the piston to the lug through the cylinder barrel. This eliminates the need for a longitudinal slot in the barrel and, therefore, the need for any dynamic seals. Breakaway forces of the magnetic field can exceed 200 lb.
A new type of rodless cylinder uses a magnetic brake for precise motion and position control. This recently introduced cylinder is designed to achieve the precise control of proportional hydraulics using simple pneumatic directional control.
In a cable cylinder, as the piston moves inside the cylinder barrel, it pulls a cable attached to both sides of the piston. The cable wraps around a pulley mounted at each end and attaches to a yoke. As the double-acting piston moves in one direction, the yoke travels in the opposite direction because of the wrap around the pulleys.

省去活塞杆，冲程加倍
通过使用更小的元件不断将机器造得越来越小这种趋势是越来越得到广泛应用的无杆气缸背后的驱动力。无杆气缸的三种主要类型是活塞耳轴版、钢索气缸、和柔性壁气缸。它们大多数都设计用于充气，但有些厂家则将它们用在低压液压应用中。
活塞耳轴设计的工作方式类似传统气缸，但它不通过活塞杆移动负载，而是从活塞的一侧伸出一个螺栓沿气缸管的纵向槽移动。在螺栓末端固定一个驱动耳轴，它直接随活塞的移动而移动。
为了将活塞与耳轴之间的槽密封，几片互相顶往的钢带在螺栓通过时分开。活塞具备不同宽度以满足负载所需的弯曲时间。活塞耳轴的冲程可超过30英尺。其选配件包括活塞开关、刹车掣、以及支撑负载并保证对齐的托架。
各种活塞耳轴气缸均在活塞内使用了一个永磁铁以产生磁场，该磁场将活塞与耳轴通过气缸管相连。这样在气缸管上就不需要纵向槽，因而也不需要任何动态密封圈了。磁场的起步阻力可超过200磅。
有一种新型无杆气缸使用刹车掣进行精确运动和位置控制。这种不久前才推出的气缸设计通过使用简单的充气方向控制可达到与液压压力成正比的精确控制。
在钢索气缸中，当活塞在气缸管内移动时，能牵引固定在活塞两端的钢索。钢索绕过安装在两端的滑轮固定在框架上。当双动式活塞沿一个方向移动时，由于有了滑轮，因而框架沿相反方向运动。

支持一下感觉挺不错的