Patent ID: 8408835

Claim:
A clamp for section tubes comprising: a shell with a pair of opposite side laterals, a front lateral, a rear lateral, a first side wall having a rear opening defined therein, and a second side wall, a fork contained in the shell and having a pair of arms and a fork neck, an end block being fixed to the pair of arms of the fork and having an end slope towards the fork neck, a slide block between the pair of arms and having a rear slope towards the end slope and a thread hole defined therein, a first and a second rigid tie bars each having a rear end pivotally linked to the fork neck of the fork, a hooked head sticking out from the front lateral of the shell and extending opposite with each other, and a middle recess facing towards each other, a pillar having two ends respectively fixed to the pair of opposite side laterals and being sandwiched between the middle recesses, one hole respectively defined in the first side wall and the second side wall of the shell, a control screw having two ends slidably and respectively contained in the holes in the first and the second side walls, at least two end protrusions respectively touching the first and the second side and a middle thread portion rotatably contained in the thread hole in the slide block, an end spring on the rear lateral and pushing the end block, a first side spring on the first side and pushing the first tie bar, and, a second side spring on the second side and pushing the second tie bar.