SYSTEM / Control System Attachment Mode Control (Only Machine Equipped with Front Attachment) Operation: 1. When the work mode is in the attachment mode position and the breaker (attachment pilot valve) is operated, the pressure sensor (attachment) detects attachment pilot pressure and sends the signal to MC. 2. At the same time, the selection information of at- tachment mode is sent to MC. 3. MC always detects the displacement angle de- tected by the pump regulator pressure sensor. 4. MC activates the pump 2 control solenoid valve and keeps the displacement angle when the dis- placement angle of pump 2 increases to the posi- tion for maximum flow rate indicated at the at- tachment mode. 5.
As the attachment is controlled by the auxiliary spool at 5-spool section in control valve, only maximum flow rate of pump 2 is controlled. Purpose: Limits the upper of maximum flow rate of pump 2 and controls the appropriate flow rate for the attachment when operating the attachment with the work mode in attach- ment mode. NOTE: When the attachment mode is shifted, the maximum flow rate setting (367 L/min (97 gpm)) at normal control (digging mode) can be selected as the table below. NOTE: If operating the attachment at digging mode, flow rate of pump 2 is kept minimum. NOTE:
As return oil from the breaker flows to the hydraulic oil tank directly without flowing through the oil cooler, hydraulic oil tem- perature increases. In order to prevent this, when operating the breaker, MC activates pump 1 flow rate control solenoid valve and increases deliv- ery flow rate of pump 1. Consequently, as oil amount through the oil cooler increases, hydraulic oil temperature does not increase and overheating is pre- vented when operating the breaker.
Q (L/min) 367 280 250 200 Pressure P T2-2-34 Mode Maximum Flow Rate Breaker Breaker 1 200 L/min (53 gpm) Mitsubishi (MKB2500SS) Breaker 2 250 L/min (66 gpm) NPK (E-220) Furukawa (F-45) Mitsubishi (MKB3000V) Breaker 3 280 L/min (74 gpm) Hitachi (HSB90S) NPK (E-225) Okada (OUB524)