Model 403 Tension Proof Tester


Our most popular tension proof tester. The Model 403 tests lumber up to 2x12 in (38x286 mm) with tensile loads up to 100,000 lbs (440 kN). This machine can satisfy most of your tensile strength testing needs for structural lumber and composite materials.

  • Largest tension proof tester with the patented wedge grip
  • Flexible and easily changed gauge lengths.
  • Unlimited maximum specimen length
  • Provides tensile quality control in MSR lumber production, qualifying the product for tensile strength rating marks in its grade stamp
  • The Model 403 is our most popular tension proof tester for dimensional lumber.
  • Tension tests lumber up to 2x12 in (38x286 mm) with up to 100,000 pounds (440 kN) of tensile force
  • Patented wedge-grip clamps hold massive jaws which squeeze tight as the tensile force is increased
  • Clamps have open ends so the length of the tested board is only limited by space in the room.
  • Testing span from 1 ft (305 mm) to 12 ft (3660 mm) between the clamps.
  • Custom testing spans may be specified at the time of order
  • Set end clamp is easily moved by hand to increase or decrease gauge length
  • Test material is inserted on-edge from either end of the machine
  • Pneumatic closure system provides initial clamping force
  • Two frame-mounted hydraulic cylinders provide tensile load
  • Options are available for displaying the maximum load attained while the specimen is loaded to failure.

The Model 403 Tension Proof Tester grips the test specimen at its ends, applies a test load by means of hydraulic clyinders, and measures the load applied. Each of the two clamps in the Model 403 contains a pair of polymersurfaced steel grip plates, for a total of 4 grip plates. There are differences in the friction characteristics of the wood/grip interface for the different wood species and different polymer grip coatings. The hard orange polymer lasts longer than the soft green polymer, but the friction characteristics of the soft polymer are better. Polymer life has been found quite acceptable for the Model 403 even with the soft polymer, and new machines are provided with soft polymer grip plates unless specified otherwise at time of order. The grip plates are interchangeable and can be recoated with either hard or soft polymer.


Test Gauge Lengths

1 to 12 ft in 1 ft increments (305 to 3660 mm in 305 mm increments) between grips for 16 ft machine. 1 to 16 ft in 1 ft increments (305 to 4877 mm in 305 mm increments) between grips for 20 ft machne.(Other gauge lengths available by special order.)

Maximum Tensile Force

100,000 lb (440 kN)

Tensile Force Actuation

10,000 psi (69 MPa) hydraulic cylinders

Maximum Tensile Stroke

4 in (102 mm)

Clamp Force Actuation

From tensile force via split inclined plane

Initial Clamp Force

Air cylinder; one on each clamp

Clamp Grip Length

24 in (610 mm)

Vertical Centering in Clamps

Provided for material widths 1.5, 2.5, 3.5, 4.5, 5.5, 7.25, 9.25, and 11.25 in (38, 63.5, 89, 114, 140, 184, 235, and 286 mm)

Material Feed

From either end of machine

Lumber Centerline Height

34 in (864 mm)

Test Material Size Range


Up to 11.75 in (290 mm)


Approx. 1.25 to 2.00 in (32 to 51 mm)


Greater than 5 ft. (1524 mm) for full grip coverage (gauge length) + 2 x (grip length). Unlimited maximum length. Shorter lengths allowed with reduction in maximum force


Force Measurement System

115 Vac 50/60 Hz 2 amp (230 Vac available)


Clean shop air at 90 psi, 0.1 cubic ft/cycle

Hydraulic Power Unit

1/2-horsepower electric pump with gauge, pressurecompensated flow control valve, and a steel reservoir

Pump Specifications

Maximum pressure

10,000 psi (69 MPa)

Oil flow at max pressure

17 in3 /min (280 mL/min)

Valve positions

retract, hold, metered advance and full advance.

Electric control

Pendant on/off switch

Electric power

1/2-hp, 50/60 Hz, single phase, 115 Vac standard, 230 Vac 50 Hz motor

Duty Cycle

Heating restrictions limit continuous testing to 30 boards followed by a 60% duty cycle.

Standard Frame

Model 403 with 16-ft frame (4877 mm), 1/2-horsepower pump, and force measurement system. (403-BAS-1501)

Optional Frame Model

403 with 20-ft frame (6096 mm), 1/2-horsepower pump, and force measurement system. (403-BAS-1502)

Tension Calibration Link

Includes two wood-faced steel paddles for insertion into the clamps; a tension load cell with steel pins for attachment to the paddles; and a readout unit. The tension calibration link, when inserted into the Model 403 Tension Proof Tester and brought up to load, gives a completely independent measurement of force for checking the force calibration up to 100,000 lbs (440 kN). (SYS-ASM-1005)