| 摘要 |
An automatic self-leveling ladder having a leveling leg axially slidably mounted within the bottom of each member of a pair of spaced vertical rung supporting members for automatically compensating for unevenness in the support surface. A rack is fixed to each of the legs and is engaged by a gear located within each of the legs that is mounted on an end of a stub shaft. A locking device is fixed on each of the rung supporting members and engages the gears upon application of the weight of the ladder on the legs to lock the legs in a selected leveling position. The stub shafts extend inwardly from the rung supporting members and are located within a complementary sized tubular telescoping member which serves as the bottom rung of the ladder. One of the stub shafts is fixed to the tubular member so the member rotates with the shaft. The shafts are joined by a spring steel strip to rotate the shaft in unison and to compensate for torsional forces exerted on the two stub shafts when in locked positions. A coil spring biases each of the stub shaft gears out of locked position with the locking devices. Upon placing the legs on a supporting surface, the weight of the ladder is sufficient to overcome the spring biasing force whereupon the legs automatically level themselves and the locking devices engage with the gears to lock the legs in a level position. Upon removal of the ladder weight from the legs the springs move the gears out of engagement with the locking devices.
|
