SuperFlow AutoDyn, Руководство оператора, Страница: 14 / 208

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Section 2 - Page 7
Place the dynamometer frame assembly so that it is on a level surface.
Reducing any twisting stress on the main frame will enhance overall
durability and improve measurement accuracy. Jack feet are provided for
easy alignment.
Differential oil cooler (optional)
On some models, a differential oil cooler may be supplied for
endurance testing. This cooler consists of a thermostatically
controlled oil-to-water heat exchanger, a circulation pump, and
an oil filter. Thermocouple temperature measurements are
provided and quick connect couplings are used.
2.4. Power Absorber Assemblies
The (optional) absorber packages are used to simulate addi-
tional inertia, or to measure power at a constant speed. The
AutoDyn can be equipped with two different absorber packages. Both
are mounted in a specific module, which attaches to the front of the
dynamometer frame. The absorbers are connected to the truck axle
differential (and thus the rolls) via a short drive-shaft. The addition of
an absorber to the system allows speed or torque control. This feature
allows the user to run constant speed, constant torque, or controlled
acceleration tests.
The load cell measures the total force applied by the vehicle and sends
an analog voltage to the CPU for conversion and measurement. Because
the axle is trunnion-mounted, all torque reaction forces are measured by
the load cell mounted on the differential and there is no need for
trunnion-mounting the absorber. This improves the accuracy of torque
measurement and makes it independent of differential oil temperature or
absorber alignment. The force measured is only as accurate as the
calibration that must be performed on the unit. If the calibration is off by
five percent, then the measurement will be off by five percent as well.
The axle has mounting points for a torque calibration arm. The calibra-
tion arm is supplied with the dynamometer.
Both types of absorber modules available for the AutoDyn are de-
scribed below.
2.4.1. Single Eddy Current absorber module
A module with a single, air-cooled eddy current absorber is attached to
the dynamometer. The load is applied by generating an electric field in
which rotors of magnetic material turn. This results in an electro-
magnetic resistance to rotation, which can be controlled by varying the
current in the coils generating the electric field.
Eddy Current absorbers achieve fast response, excellent stability, and
high torque at low speeds. An air-cooled eddy current absorber must
dissipate all power into the air circulating through the rotors. For high
power applications, the rotors will heat up rapidly which will reduce
their power capability. For this reason, an air-cooled eddy current