| 摘要 |
A food freezing tunnel has a trough member 42 and a roof member 40. In order to gain access to the interior of the tunnel, for example for purposes of cleaning the tunnel, the trough member 42 is able to be raised and lowered. Jack means l08 housed in the respective legs 82 of the tunnel are driven by an electric motor l05 to lower and raise the tunnel. The trough 42 has counterweights l2l. Typically the jack includes a rotary screw-threaded shaft ll0 which carry a nut ll2 connected to a chain ll4 which travels over pulleys ll6 and ll8 and which is secured to the trough member 42. |
