Drive controlling mechanism

Abstract

A crawler type travelling vehicle comprises in combination: an endless belt including a number of segments flexibly connected with each other to crawl on the earth; a sprocket wheel drivably engageable with the endless belt and having an axial wheel bore extending axially thereof; a motor housing inserted in said axial wheel bore to rotatably support the sprocket wheel through two bearings with the mid-circumferential plane of the sprocket wheel positioned between the mid-circumferential planes of the bearings; a fixed frame positioned axially inwardly of the sprocket wheel to securely support the motor housing and having an axial frame bore in axial alignment with the axial wheel bore; a hydraulic motor accommodated in the motor housing and having a rotary shaft; a reduction gear unit positioned axially outwardly of the sprocket wheel and within the width of the endless belt to operably be connected with one end portion of the rotary shaft in driving engagement with the sprocket wheel; a control block disposed within the width of the endless belt and securely connected with the axially inner face of the motor housing to rotatably receive the other end portion of the rotary shaft; and a pair of inlet-outlet passages in fluid communication with the hydraulic motor to allow fluid under pressure to pass therein for imparting rotation of the hydraulic motor.