BLADE GP-ANGLING 4839280 - Caterpillar

Straight Travel Control
Introduction
Control Valve Compartment
(1) Right travel. (2) Straight travel. (3) Left travel.
Hydraulic Schematic (Partial) (Only Right and Left Travel Activated)
(1) Right travel control valve. (2) Straight travel control valve. (3) Left travel control valve. (4) Main control valves. (5) Line. (6) Line. (7) Upper pump. (8) Lower pump.If the upper structure or implements are operated while the machine is traveling, straight travel control valve (2) assures a straight travel of the machine. Straight travel control valve (2) also allows better control of operations such as pipe laying or placement of timbers.When the machine travels with no swing or implement operation, oil from upper pump (7) drives the right travel motor and oil from lower pump (8) drives the left travel motor. Since both travel circuits are separated, the machine continues to travel straight, unless a difference in travel resistance occurs between the right and left tracks.Without the straight travel system, a swing and/or implement operation (while performing a travel operation) would cause upper pump (7) and lower pump (8) to supply varying amounts of pump oil to the track motors. This would cause the machine to not travel straight.The straight travel system assures the machine to travel straight when circuits other than the travel circuits are simultaneously operated. When straight travel control valve (2) is activated by pilot pressure, the following occurs:1. Upper pump (7) supplies oil not only to the right travel circuit but also to the left travel circuit to drive both motors in parallel.2. The swing and implement circuits get their supply of pressure oil from lower pump (8). When the machine is traveling, the swing and implement circuits do not require a large amount of flow. They are operated at speeds low enough to keep the machine stable. The remainder of the pressure oil is divided between the right and left travel circuits.Implement And Travel Operation
Hydraulic Schematic (Partial) (Boom and Travel Activated)
(1) Parallel feeder passage. (2) Main control valves. (3) Stick I control valve. (4) Swing control valve. (5) Left travel control valve. (6) Center bypass passage. (7) Right travel control valve. (8) Bucket control valve. (9) Boom I control valve. (10) Center bypass passage. (11) Passage. (12) Passage. (13) Passage. (14) Passage. (15) Straight travel control valve. (16) Passage. (17) Passage. (18) Pilot passage. (19) Pilot passage. (20) Pilot passage. (21) Passage. (22) Passage. (23) Pilot passage. (24) Pilot passage. (25) Passage. (26) Parallel feeder passage. (27) Pilot oil manifold. (28) Upper pump. (29) Drain line. (30) Line. (31) Line. (32) Pilot pump. (33) Lower pump.When the boom control lever is activated during travel, there is pilot oil flow from the travel pilot control valves through pilot passages (20) and (24) to right and left travel control valves (7) and (5). For a boom operation, pilot oil flows from the boom pilot control valve through pilot passage (23) to boom I control valve (9).As the boom I control valve is operated, passage (22) is closed. There is an increase in pilot pressure