| 摘要 |
A changeable sign in which the letter panels form the background of the sign as well as carrying the indica. The letters carry horizontal tongues on their upper and lower edges which fit into grooves locking the letters therein. The framework of the changeable sign is mounted for vertical movement so that it may be lowered to the ground for changing the letters. End caps lock the letters in their groove support to prevent pilferage. Moveable guide poles are used to guide the framework as it is moved vertically to prevent damage to the sign and injury to the operator. Counter weights are used to support the weight of the sign through a system of pulleys so that the sign can be easily moved up and down as required.
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