| 摘要 |
<p>A pneumatic counterbalance spring (10) includes a hollow cylinder (15) defining a first internal chamber (20) divided into a compression compartment (50) and an extension compartment (55) by a piston (25) movably mounted in the chamber. The compression compartment (50) contains pressurized gas and a seal assembly (60) which is mounted on the piston (25) prevents the gas from escaping into the extension compartment (55). A piston rod is slidably mounted in the open end of the piston. The piston rod (30) includes a hollow portion defining a second internal chamber (125) which is fluidly connected to the compression compartment (50) by a flow passage (140). A gas permeably insert (150) may be positioned in the flow passage to provide restricted rate flow of gas through the flow passage.</p> |
