Here's one: Servo - Generic High Torque (Standard Size) - ROB-11965 - SparkFun Electronics. No idea of course whether it would suit your application, but it will at least behave as you expect.
Here's one: Servo - Generic High Torque (Standard Size) - ROB-11965 - SparkFun Electronics. No idea of course whether it would suit your application, but it will at least behave as you expect.