Level

Abstract

A level comprises a frame defining first and second parallel channels and first and second rails fitted slidingly in the first and second channels respectively. The level is adjustable in length by sliding the rails in the respective channels of the frame.

I claim:  
     
         1 . A level adjustable between a retracted condition and an extended condition, the level comprising: 
 a frame including a first guide surface and a guide member having a sliding surface;    a rail including a second guide surface and a slide having a sliding surface, the rail mounted to the frame with the second guide surface coplanar with the first guide surface, and with the sliding surfaces of the frame and the rail contacting one another and sliding relative to one another as the frame and rail are moved between the retracted and extended conditions, wherein at least one of the sliding surfaces is treated to prevent sticking; and    an indicator mounted to one of the frame and the rail, the indicator readable by a user to determine if the guide surfaces are in either a horizontal or a vertical position.    
     
     
         2 . The level of  claim 1  further comprising a biasing means coupled to the rail and the frame, the biasing means urging the sliding surfaces against one another to increase the friction between the sliding surfaces and frictionally hold the rail and the frame in any position between the retracted and extended conditions.  
     
     
         3 . A level adjustable between a retracted condition and an extended condition, the level comprising: 
 a frame including a first guide surface and a guide member;    a rail including a second guide surface and a slide, the rail mounted to the frame with the second guide surface coplanar with the first guide surface, and with the slide adjacent and slidable relative to the guide member between the retracted condition and the extended condition;    a first indicator mounted to the frame, the first indicator readable by a user to determine if the guide surfaces are in either a horizontal or a vertical position; and    a second indicator mounted to the rail, the second indicator readable by a user to determine if the guide surfaces are in either a horizontal or a vertical position.    
     
     
         4 . A level adjustable between a retracted condition and an extended condition, the level comprising: 
 a frame including a first guide surface and an upper guide member and a lower guide member, the upper guide member defining a channel and including a sliding surface, the other guide member having a leaf spring mounted thereon;    a rail including a second guide surface and a slide having an upper sliding surface and a lower sliding surface, the rail mounted to the frame with the second guide surface coplanar with the first guide surface, and the slide disposed at least partially in the channel, wherein one of the sliding surfaces of the rail contacts the sliding surface of the frame and the other sliding surface of the rail contacts the leaf spring, the slide moving relative to the guide members as the frame and rail are moved between the retracted and extended conditions; and    an indicator mounted to one of the frame and the rail, the indicator readable by a user to determine if the guide surfaces are in a desired orientation.    
     
     
         5 . The level of  claim 4  wherein the leaf spring biases the sliding surface of the rail against the sliding surface of the frame to frictionally hold the rail and the frame in any relative position between the retracted and extended conditions.  
     
     
         6 . The level of  claim 4  wherein the leaf spring includes two wings extending from a central mount.