HYDRAULICS
4181383 First Edition 6-23
6
Instrument Test Procedure
Instrument Test Overview
The following tests are specifically designed to approach
hydraulic testing on a system level. Each component
within the system represents a portion of the total system
leakage. An internal leakage percentage for each
component will be calculated and recorded, enabling the
technician to view the system performance issue more
completely. The test results will help the technician to
determine which repairs will best remedy the
performance issue experienced by the machine user.
The internal leakage percentage ranges are as follows:
0—10% = Good
11—20% = Marginal
21% and beyond = Bad
Example: Cutting Unit System Performance
Complaint
The machine operator reports the mower is not cutting
correctly.
Troubleshooting must first be performed to rule out a
cutting unit adjustment issue. Once the issue is known to
be component related, the entire cutting unit system is
tested as outlined. The calculated system leakage is
35%; a result which requires the testing of individual
components. This result can also be interpreted as the
system is 65% efficient.
The remaining components in question are as follows:
rear cutting unit pump, deck valve, left rear cutting unit
motor, center cutting unit motor, and right rear cutting unit
motor. Following the procedures as outlined, test each
individual component, then calculate and record leakage
percentages.
The results from this test reveal leakage of 5% in the rear
cutting unit pump, 10.5% in the deck valve, 20% in the left
rear cutting unit motor, 5.6% in the center cutting unit
motor, and 4.4% in the right rear cutting unit motor.
Although all the components lend to the overall circuit
leakage, only the left rear cutting unit motor, which is at
the extreme end of the marginal range, would be
considered for repair/replacement.
Formulas:
Cutting Unit Motor and Deck Valve
Loaded Flow from previous component – Loaded Flow
from current component / Loaded Flow from previous
component x 100 = Leak Percentage
Circuit and Rear Cutting Unit Pump
No Load Flow – Loaded Flow / No Load Flow x 100 =
Leak Percentage
Calculations:
Circuit Test
No Load Flow = 10 gpm
Loaded Flow = 6.5 gpm
10 – 6.5 / 10 x 100 = Total Circuit Leakage 35%
Rear Cutting Unit Pump Test
No Load Flow = 10 gpm
Loaded Flow = 9.5 gpm
10 – 9.5 / 10 x 100 = Rear Cutting Unit Pump Leakage
5%
Deck Valve Test
Loaded Flow from rear cutting unit pump test = 9.5 gpm
Loaded Flow from deck valve test = 9 gpm
10 – 9 / 9.5 x 100 = Deck Valve Leakage 10.5%
Left Rear Cutting Unit Motor Test
Loaded Flow from deck valve test = 9 gpm
Loaded Flow from left rear cutting unit motor test = 7.2
gpm
9 – 7.2 / 9 x 100 = Left Rear Cutting Unit Motor Leakage
20%
Center Cutting Unit Motor Test
Loaded Flow from left rear cutting unit motor test = 7.2
gpm
Loaded Flow from center cutting unit motor test = 6.8
gpm
7.2 – 6.8 / 7.2 x 100 = Center Cutting Unit Motor Leakage
5.6%
Right Rear Cutting Unit Motor Test
Loaded Flow from center cutting unit motor test = 6.8
gpm
Loaded Flow from right rear cutting unit motor test =
6.5 gpm
6.8 – 6.5 / 6.8 x 100 = Right Rear Cutting Unit Motor
Leakage = 4.4%
To Next Page
Loading...
Need help?
General
