SUPPORT 2M7872 - Caterpillar

Operator Console
(11) Moldboard mode selector switch. (12) Moldboard elevation switch.
Ground Station
(12) Moldboard elevation switch.The moldboard system controls moldboard elevation either manually or automatically. The control console contains moldboard mode selector switch (11) and moldboard elevation switch (12). Two moldboard elevation switches (12) are located at the rear of the machine for access from the ground. Moldboard mode selector switch (11) sets the mode of operation of the moldboard to either manual or automatic. Moldboard elevation switches (12) raise or lower the moldboard. When a moldboard elevation switch (12) is released, the moldboard is allowed to float over the cut surface. The moldboard switches are inactive when the machine is at the service elevation height.Manual Mode
When moldboard mode selector switch (11) is in the MANUAL mode, the moldboard floats over the cut surface. The weight of the moldboard applies a downward pressure. If moldboard elevation switch (12) is activated, the moldboard will react and then return to the float position when the switch is released. In the manual mode, moldboard elevation switch (12) can be in the raise position, the float position, or the lower position.Float Position
When moldboard elevation switch (12) is not held in the raise or lower positions it is in the float position. When in the float position, oil from auxiliary hydraulic pump (1) to cylinders (10) is blocked by control valve (3). The rod and head end of moldboard cylinders (10) are open to hydraulic tank (6). The weight of the moldboard is the only downward pressure applied. The moldboard is kept in contact with the freshly cut surface. If an obstruction is encountered, relief valve (9) will bypass oil from the head end of cylinders (10) when a pressure of 10 330 kPa (1500 psi) is exceeded.Raise Position
Oil from auxiliary pump (1) flows to control valve (3). Moving moldboard elevation switch (12) to the RAISE position shifts the spool of control valve (3) to port oil to the rod end of moldboard cylinders (10). The moldboard raises.Return oil from the head end of cylinders (10) flows through control valve (8). Control valve (8) allows hydraulic oil from the cylinder head end to return to hydraulic tank (6).The moldboard can also be activated by the rotor service door switch. When the rotor service door switch is activated, the moldboard will raise. When the moldboard reaches the fully raised position, pressure in the rod end of the cylinder increases. When the pressure reaches 13 780 kPa (2000 psi), the pressure switch (4) is energized activating the rotor service door control valve. The rotor service door control valve is explained in the Rotor Service Door System section of this module.Lower Position
Oil from auxiliary pump (1) flows to control valve (3). Moving the moldboard elevation switch to the LOWER position spool shifts control valve (3) to supply auxiliary hydraulic pump oil the head end of cylinders (10) and moves the moldboard downward.Return oil from the rod end of cylinders (10) flows through control valve (3) to hydraulic tank