Different Application Standards
The standard of The vertical rebound resilience tester is ASTM D 2632
The pendulum rebound resilience tester’s standards include BS ISO 4662, ASTM D 7121, DIN 53512, DIN 53573, ASTM D 1054, etc.
Obviously, the latter applies more standards than the former.
Different Requirements for Specimens
The vertical Rebound Resilience Tester is mainly used to test all solid rubber, and is not suitable for cellular rubbers.
The pendulum rebound resilience tester is used to test the hardness of rubber between 30 IRHD and 85 IRHD, regardless of vulcanized rubber or thermoplastic rubber. (You can use a rubber hardness tester to test the hardness of the sample before preparing the sample).
Different Test Principle
The vertical Rebound Resilience Tester determines the ratio of rebound height to drop height of a metal plunger of specified mass and shape after it falls on the specimen.
The Pendulum Rebound Resilience Tester is to determines the ratio of the energy returned to the energy applied when a hammer with a spherical indentor impacts a specimen under the prescribed conditions.
Different Test Methods
The vertical rebound resilience tester:
You raise the plunger to a height of 400 mm above the surface of the sample, and then release the plunger sliding on the plunger guide to impact the specimen in a vertical drop, to measure the rebound height of the plunger visually.
The pendulum rebound resilience tester:
You raise the pendulum rod and lock it in a horizontal position, then release the pendulum peen, and the spherical indentor attached to the hammer impacts the lower specimen laterally along an arc. The pointer on the analog scale will move the corresponding angle of rebound synchronously. You can read the rebound reading.