The linear travel valve is next to the left travel control spool in the quadruple directional valve. When the travel and working (or swing) devices are simultaneously operated, the valve connects the left and right travel oil paths to each other, and the flow rate to the left and right travel motors is equal The motor rotates at the same speed to ensure that the excavator travels straight.
(1) When only traveling, there is no pilot pressure oil from the shuttle valve of the PPC valve to the straight travel valve, so the left and right traveling oil passages are closed, and the oil passages on both sides remain independent.
(2) When the walking and working (or slewing) devices are operated at the same time, the pilot pressure oil from the walking shuttle valve pushes the slide valve of the linear travel valve to the right. The travel oil passage is connected to the right travel oil passage, and supplies equal pressure oil to the left and right travel motors, so that the travel motors on both sides rotate at the same speed, and the excavator travels straight.
