Patent ID: 8721508

Claim:
A counterbalance device for weight training, comprising: a brake unit including an outer cylinder, a resistant spring, a screw rod, and an adjusting member, with the resistant spring received in the outer cylinder, with a gear engaged to a front end of the resistant spring, with the screw rod extending through the outer cylinder and the resistant spring and including a threaded section and a front section, with the front section of the screw rod extending through the gear such that the gear and the screw rod can be turned together, with the front section of the screw rod connected with a steel cable of a weight training apparatus, with the adjusting member screwing around the threaded section of the screw rod and including an outer thread disposed on an outer circumference thereof, with the adjusting member being threadedly engaged in the resistant spring; and a control unit including a motor, with the motor coupled with a transmission gear engaged with the gear of the brake unit, wherein when the screw rod is pulled, the adjusting member is moved with the screw rod together to compress the resistant spring; and wherein when the motor is actuated, a position of the adjusting member relative to the resistant spring can be changed, so that a number of spring coils of the resistant spring which can be compressed are also changed.