MAN - BBR3 - REV: Original | C. System Overview
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The load frame is constructed with a horizontal shelf that extends across the top of the base unit to provide supports
to suspend the lower portion of the load frame in the fluid bath. The upper part of the load frame is covered by an
access panel that permits the user to easily view the top of the loading shaft. This panel also provides access to
the weight pan for easy calibration of the load cell and the Linear Variable Differential Transformer (LVDT). Two low
voltage, sealed lamps are mounted in the base of the load frame in order to illuminate the specimen in the fluid bath.
The load frame is made up of an LVDT shaft, weight pan, air bearing, load shaft, load cell, and adapter. A metal plate
cover is mounted to the front of the load frame and serves to protect the load cell from splashing fluid and minimize
the effect of fluid movement on the load nose.
Specimen Support
The bottom half of the load frame consists of an anvil with two metal supports designed for alignment of the
specimen. These specimen supports have a 3 mm contact radius and are fixed 102 mm apart from each other. They
are designed to align samples that are approximately 127.00 mm x 12.70 mm x 6.35 mm.
Resting on each of the anvil’s specimen supports are two anvil adapters (see Figure C.7). During crack sealant
testing these anvil adapters need to be removed by lifting STRAIGHT UP on the adapter and pulling it off of the guide
pin. The load frame should be removed from the bath and allowed to warm to room temperature before removing the
anvil adapters.
The specimen supports and lower portion of the load frame are designed to be submerged in the constant-
temperature fluid bath during the test. The fluid in the bath provides a buoyant force that counterbalances the weight
of the specimen.
Air Bearing
The BBR3 incorporates an air bearing to provide frictionless loading performance. The air bearing control system
requires a constant 60 – 65 psi (414 – 448 kPa) minimum clean and dry air supply, @ Class 3 Quality max particle
of 5um. The air pressure to the air bearing is controlled by a set of high-precision air regulators located on the front
panel of the base unit.
Figure C.7 - Load Frame with Anvil Adapters
Figure C.6 - Load Frame without Anvil Adapters