190301i Flashcards Preview

HET3 Hydraulics 190301 > 190301i > Flashcards

Flashcards in 190301i Deck (17):
1

The main disadvantage of electrically controlled hydraulic systems is that they are:

not able to provide variable speed control.

2

The function of the bucket kickout on a wheel loader is to hold the bucket control
lever in the rollback position until the bucket reaches the correct digging position.T/F

true

3

Proximity switches are commonly used in loader bucket kickout and lift height
control systems. When the detector plate is in close proximity to the switch, the
switch is:

closed.

4

Loader bucket kickout position and lift height can be adjusted by

adjusting the position of the proximity switch in relation to the detector plate.

5

The function of input devices in an electronic controlled hydraulic system is to:

send information in the form of electrical signals to the ECU.

6

An example of a typical reference voltage sensor that sends a discreet voltage signal
is a:

switch

7

Lever operated potentiometers that are used as operator controls are called

joysticks

8

In order to control a hydraulic system, the electronic control unit (ECU) takes input
signals from ___________________, compares them to ______________________
and, when necessary, sends a _________________________ to output components.

parameters established in an internal
program / voltage

9

Self-diagnosis is a feature that is often incorporated into the internal program of the
ECU. The self-diagnosis program generates a __________________ that indicates
the location and nature of system malfunctions.

fault code

10

The function of output components (actuators) of an electronic control system is to

convert electrical output signals from the ECU into output action.

11

Solenoids used in electrical control systems often function in discrete positions.T/F

true

12

The force created by a proportional solenoid is proportional to:

output voltage signal from the ECU.

13

A pulse width modulated signal is used to actuate proportional solenoids because it:

generates less heat than a DC signal.

14

Why do closed loop electronic control system offer more accurate control than open loop systems?

Closed loop electronic control systems include sensors that send a feedback signal to
the ECU from the hydraulic actuator. By monitoring actuator motion, the ECU can
provide more accurate control of its position, velocity, or acceleration

15

How does pulse width modulation prevent the build-up of heat in solenoids?

By varying the total applied voltage to the solenoid, less current flows through the
coil, therefore, less heat is generated.

16

Name one (1) way to prevent stiction

By using dither to keep the spool moving or vibrating slightly, stiction (or hysteresis)
is prevented.

17

Better filtration and maintenance procedures are required on electrohydraulically
equipped machines because __________

they have a narrower tolerance to dirt and grit in the
fluid.