Boom Lift Crawler Jib with Hydraulic Actuation 1D Load (Test Harness)
This example models a hydraulic system that extends a jib for a boom lift basket. In this test harness, the load is approximated as a inertia of constant value. It ignores the changes that take place as the parallelogram mechanism expands and assumes the actuator is always acting exactly opposite the direction of gravity.
This model is a test harness from the main model (see documentation).
Component Under Test
The component under test is a hydraulic system to extends a an actuator that raises a boom lift basket. A double-acting cylinder with two counterbalance valves extends to open the raise the jib. The counterbalance valves lock the cylinder in place when the 4-way valve returns to center. The lock persists if a hose upstream bursts so the boom does not collapse. The "counterbalance" in the valves keeps the cylinder from running ahead of the pump under gravity. This condition would cause it to ratchet were it fitted with the pilot check valves of the outriggers.
Simulation Results: Jib Sequence
The plots below shows the result of a test sequence designed to raise and lower the jib. The test sequence includes signals for all valves so that the test sequence can also be run on the full model.
Below is the corresponding prescribed motion for the test. This allows testing on a full model that has motion for any combination of the actuators.
Motion of the lift, extend, and jib cylinders along with applied actuator force.
Hydraulic pressures in the actuators along with actuator position.