Dial Weight Dynamometers

Dial Weight Dynamometer

Product Description

The most important characteristic of any measurement instrument is repeatability and accuracy. The Magtrol Dial Weight Dynamometer uses the combination of a Hysteresis Brake and gravity to insure constant, reliable results. The brake torque rise is directly proportional to applied current. The calibrated weight system provides readings in standard engineering units through the use of multiple torque range scales provided on each size dynamometer.

Magtrol Dial Weight Dynamometers are a lower cost alternative to our standard (load cell) Hysteresis Dynamometers. The dial weight dynamometers are easy to operate, provide repeatable and accurate results, and will operate for many years with minimal maintenance. A Magtrol Dial Weight Dynamometer System can only operate manually in an open loop mode.


Range:Models as low as 0.5 oz·in full scale to 200 lb·in Full scale. Each dial weight dynamometer comes with three weights to cover the three specified ranges.
Calibration:Dynamometers listed show English calibration as standard. Metric scales are also available. Magtrol Dynamometers are certified to Mil-STD 45662A and are NIST traceable.
Variable Load Capacity:Load can be adjusted from no load to full scale through simple potentiometer control on power supply.
Torque Independent of Speed:Magnetically coupled hysteresis brake provides smooth torque application independent of shaft speed. This permits testing motors from no load to locked rotor or armature.

Optional Equipment

Model 5200-2Power Supply
Model 5210-2Current-Regulated Power Supply
Model 5250-2Current-Regulated Power Supply
Model 3411:Torque/Speed Display (used with dial weight dynamometer to display speed only)

Specifications and Drawings

ModelFull Scale Torque (Range One)Full Scale Torque (Range Two)Full Scale Torque (Range Three)Maximum Operating Speed (RPM)Power Ratings - 5 Minutes (Watts)Power Ratings - Continuous (Watts)Downloads
HD-106-10.5 oz·in1 oz·in2 oz·in30,000357pdf | step
HD-400-12 oz·in8 oz·in16 oz·in20,00020055pdf | step
HD-400-28 oz·in16 oz·in32 oz·in20,00020055N/A
HD-500-125 oz·in50 oz·in100 oz·in15,00040080step
HD-600-150 oz·in100 oz·in200 oz·in10,000600100pdf
HD-700-1100 oz·in200 oz·in400 oz·in10,000700150pdf
HD-705-1200 oz·in400 oz·in800 oz·in8,0001400300pdf

All dynamometer models are within 1% accuracy, with the exception of the following:

HD-106-10.5 oz·in range is 3.5%
HD-106-11.0 oz·in range is 2%
HD-400-12.0 oz·in range is 2%
HD-400-18 oz·in range is 2%
HD-400-28 oz·in range is 2%
HD-500-125 oz·in range is 2%

System Options

To help you select the components for your motor testing system, this table shows which (currently available) electronics and software support Magtrol’s different types of dynamometers.

ModelDescriptionHysteresis Dynamometers (including ED Series)Eddy-current DynamometersPowder Brake DynamometersDial Weight Dynamometers
DSP7000High-Speed Programmable Dynamometer Controller
6200Dynamometer Controller/Readout
TSC 401Torque/Speed Conditioner
5500Dynamometer Switch Box
5501Dynamometer Switch Box
M-TEST 7Motor Testing Software
DES 410/411Power Supply
5241Power AmplifierRequired for HD-825 Only
5200Power Supply
5210Current-Regulated Power Supply
5250Current-Regulated Power Supply
TABDynamometer Tables
AMFAdjustable Motor Fixtures
FMFFixed Motor Fixtures
PTT-Slot Base Plate
FRSFree-Run Speed Sensor
SBB 14Signal Breakout Box

Dynamometer Selection

Magtrol Dynamometers cover a wide range of Torque, Speed and Mechanical Power ratings. To select the appropriate size Dynamometer for your motor testing needs, you will need to determine the Maximum Torque, Speed and Power applied to the Dynamometer:

Maximum Torque

It is important to consider all torque points that are to be tested, not only rated torque, but also Locked Rotor and Breakdown Torque. Dynamometer selection should initially be based on the maximum torque requirement, subject to determining the maximum power requirements.

Maximum Speed

This rating is to be considered independent of torque and power requirements, and is the maximum speed at which the Dynamometer can be safely run under free run or lightly loaded conditions. It is not to be considered as the maximum speed at which full braking torque can be applied.

Maximum Power Ratings

These ratings represent the maximum capability of the Dynamometer Braking System to absorb and dissipate heat generated when applying a braking load to the motor under test. The power absorbed and the heat generated by the Dynamometer is a function of the Torque (T) applied to the motor under test, and the resulting speed (n) of the motor. This is expressed in these power (P) formulas:

SI:P (watts)=T (N·m)xn (rpm)x(1.047 × 10-1)
English:P (watts)=T (lb·in)xn (rpm)x(1.183 × 10-2)
Metric:P (watts)=T (kg·cm)xn (rpm)x(1.027 × 10-2)
All of Magtrol's controllers, readouts and software calculate horsepower
as defined by 1 hp = 550 lb·ft / s. Using this definition:
hp=P (watts)/745.7
To calculate power, use Magtrol's online motor power calculator

The Dynamometer’s ability to dissipate heat is a function of how long a load will be applied. For this reason, the Maximum Power ratings given are based on continuous operation under load, as well as a maximum of 5 minutes under load.

To safely dissipate heat and avoid Dynamometer failure, the maximum power rating
is the most important consideration in selecting a Dynamometer.