Sheaves mount a carriage on a skyline for yarding logs. A load line having a hooked end hanging from the carriage extends through another sheave on the carriage to a winch on a yarder at one end of the skyline. Brakes actuated by hydraulic cylinders are operable to lock the carriage to the skyline and the load line to the carriage. The skyline brake normally is released and the load line brake normally is set so that hauling in or paying out of the load line by the yarder winch effects movement of the carriage along the skyline. A hooker on the ground actuates setting of the skyline brake and releasing of the load line brake by pressing a button on a radio transmitter which signals mechanism on the carriage to supply hydraulic liquid under pressure from an accumulator to the brake cylinders, and also to a hydraulic motor which drives the load line sheave to lower the load line from the carriage. The hooker receives the load line, hooks a load of logs and signals the yarder operator to haul in the load line to hoist the log load, whereupon the brakes are returned to their normal conditions so that further hauling in of the load line moves the carriage and its log load to the yarder. The accumulator is regenerated to replenish its hydraulic liquid under pressure by a hydraulic pump driven by rotation of the load line sheave as the log load is hoisted and/or by rotation of a skyline sheave as the carriage is moved to the yarder.