Operating Speed; Checking Procedure Of Each Speed; Gravity Fall Of Cylinder - Kubota U20-3 Workshop Manual

U20-3, U25-3 WSM
e. Operating speed
[Points]
(1) Measure the time required for full stroke with the standard front attachments without load.
(2) Repeat the measurement several times, obtain the average and adopt it as measured value.
(3) When two kinds of measured value such as for forward/backward and for right swivel/left swivel can
be obtained, do not work out the average.
(4) Pay full attention to the surrounding.
[Conditions]
(1) The engine should be run at maximum rpm.
(2) The hydraulic oil temperature should be 50±5°C.
(3) Measurement should be done on a flat ground.
(4) Take the measurement after each operation has been done several times without load.

[1] Checking procedure of each speed

1) Gravity fall of cylinder

2) Boom cylinder
3) Arm cylinder
1. Place the machine on a level place. Crowd the
bucket. (72 kg)
2. Fully retract the arm cylinder and fully extend
the bucket cylinder.
3. Adjust the bucket bottom approx. 1 m above
the ground.
4. Mark the boom, arm and bucket cylinder rods.
5. Measure the amount of gravity fall 10 minutes
later, using a measuring scale.
Hydraulic oil temp: 50±5°C
1. Fully retract the arm cylinder and bucket
cylinder.
2. Operate the engine at maximum rpm.
3. Measure the time required for the movement
from the ground to the cylinder end.
Note: Cushion operating time is not included.
U20-3
Extension 2.5 to 3.1 sec. Retraction 2.6 to 3.2 sec.
Canopy
Cabine
Extension 2.1 to 2.7 sec. Retraction 2.2 to 2.8 sec.
U25-3
Extension 2.1 to 2.7 sec. Retraction 2.4 to 3.0 sec.
Canopy
Cabine
Extension 2.1 to 2.7 sec. Retraction 2.3 to 2.9 sec.
1. Bring the boom and arm into the postures as
shown in the figure.
2. Operate the engine at maximum rpm.
3. Measure the time required for full stroke of the
arm cylinder.
U20-3
Extension 2.3 to 2.9 sec.
U25-3
Extension 2.2 to 2.8 sec.
IV-S-39
Hydraulic system (Service section)
Retraction 2.4 to 3.0 sec.
Retraction 2.4 to 3.0 sec.