10) DIG FUNCTION DRIFT CHECK (1) Measure dig function drift, which can be caused by oil leakage in the control valve and boom, standard arm, and standard bucket cylinders, with the loaded bucket. When testing the dig function drift just after cylinder replacement, slowly operate each cylinder to its stroke end to purge air. (2) ① Preparation Load bucket fully. Instead of loading the bucket, weight( W ) of the following specification can be used. · W=M 3 Ч 1.5 Where : M 3 =Bucket heaped capacity( m 3 ) 1.5=Soil specific gravity Position the arm cylinder with the rod 20 to 30 mm extended from the fully retracted position.
Position the bucket cylinder with the rod 20 to 30 mm retracted from the fully extended position. With the arm rolled out and bucket rolled in, hold the bucket so that the height of the bucket pin is the same as the boom foot pin. Keep the hydraulic oil temperature at 50 ± 5 C . ② ③ 290LC7MS05 ④ ⑤ (3) Measurement ① ② Stop the engine. Five minutes after the engine has been stopped, measure the changes in the positions of the boom, arm and bucket cylinders. Repeat step ② three times and calculate the average values. ③ (4) The measured drift should be within the following specifications. Unit :
mm / 5 min 7-13 Model Drift to be measured Standard Ma ximum allowable Remarks R800LC-7A Boom cylinder 10 below 20 Arm cylinder 10 below 20 Bucket cylinder 40 below 50