Abstract: A safety brake is provided for a cement truck chute to immobilize the chute from lateral movement relative to the cement truck chassis. Movement of the cement truck chute is controlled by a ram which is secured to a vertically oriented ram pivot axle rotatably mounted in a sleeve secured to the truck chassis. A first horizontal brake pad is located concentrically about the ram pivot axle and is immobilized relative to the chassis. The safety brake includes a pneumatic actuator having a housing and a plunger actuable for reciprocal movement relative to the housing. A flat, horizontal ram coupling plate is rigidly secured to the ram pivot axle and holds the pneumatic actuator housing at a spaced elevation thereabove with the pneumatic actuator plunger coaxially aligned with the ram pivot axle. A horizontal intermediate plate is located between the ram coupling plate and the pneumatic actuator housing and is secured to the pneumatic actuator plunger.