Firefighters have one of the most dangerous and demanding jobs in the public’s eye. They are called upon to face complex fires or natural disasters to save lives or property. Innovative technology to help protect people and property is in high demand from firefighting forces around the world. This demand led Crash Rescue Equipment to team up with Parker’s Cylinder Division to design a telescoping nozzle on fire trucks that allow the nozzle to penetrate composite fibers and be placed inside small door openings or other restricted areas.
“Our Snozzle is a quick attack tool that can penetrate all current building, aircraft, automobile or train container materials including composite panels. By using Parker’s Helac hydraulic rotary actuator to position our piercing nozzle, we can quickly penetrate and maneuver into tight spaces in a variety of aviation and municipal applications,” stated Grady North, chief engineer for Crash Rescue Equipment.
Before using Parker’s Helac rotary actuator, Crash Rescue Equipment used two electric motors to position the piercing and water volume nozzles on the telescopic booms found on the fire trucks. When the object was pierced, a load was also put on the water volume nozzle, taxing the motors. The result of this overload condition caused the motors to slip and lose positioning control of the piercing nozzle.
Crash Rescue Equipment changed the overall design of the telescoping boom assembly to overcome this problem. They separated the function of the piercing nozzle from the water volume nozzle and used Parker’s helical, hydraulic rotary actuator to stow and deploy the piercing nozzle through 180 degrees on the telescopic boom. “Because of the inherent (zero-drift) features of a Parker’s Helac rotary actuator, our piercing nozzle could receive higher torque loads and hold side loads during piercing operations,” said North.
It’s the operating technology that makes Parker’s Helac hydraulic rotary actuators unique and offers a powerful combination of features – high torque and moment loads capacities, high angles of rotation, and compact configurations. Sliding-spline operating technology replaces multiple components and functions as a rotating device, mounting bracket, and bearing, all-in-one. This innovation converts linear piston motion into a powerful shaft rotation.
Each actuator is composed of two moving parts – the central shaft and piston. Helical spline teeth on the shaft engage matching teeth on the piston’s inside diameter. The second set of helical splines on the piston’s outside diameter mesh with the gear in the housing. When hydraulic pressure is applied to the piston, it moves axially, while the helical gearing causes the piston and shaft to rotate simultaneously.
Crash Rescue Equipment looked into several electric positioning alternatives before proceeding with a hydraulic rotary actuator. They wanted to avoid adding hydraulic lines to the internal electrical flex tube if at all feasible. They began their search with electric linear cylinders, yet quickly discovered that the geometry wouldn’t fit the application and that the cylinders also needed a much higher degree of rotation. Additionally, cylinders have external rods and linkages that would increase the maintenance costs associated with particle contamination to the electric circuitry.
Electric motors were also researched. This possibility failed to offer the torque requirements or mounting strength needed for the piercing nozzle application. The selected rotary actuator provided the engineers with compact configurations, 180° of smooth rotation, and a durable, enclosed envelope without any external moving parts. It also offered torque output to 740,000 inches per pound, even though only 4,200 inches per pound of torque were needed to operate the piercing nozzle.
The Helac L20-4.5-180° rotary actuator was mounted directly onto the boom. Because of the actuator’s high radial and torque capacity, auxiliary bearings are not needed. All external forces are supported solely by the actuator.
This article was contributed by Jessica Howisey, marketing communications manager and Daniel Morgado, applications engineer, Helac Business Unit, Cylinder Division and was originally published by Pneumatics Tips Fluid Power World Resource .