There may come a time when replacing a linear actuator or a control box is necessary to ensure proper or enhanced operation. In the case of a medical care bed linear actuator, it may need to be upgraded to allow for a higher output force. But what happens when you need to replace a control box or linear actuator with 3rd party equivalents? This guide will walk you through whether retrofitting of different linear actuators and control boxes is even possible, and what to look out for when making a final decision.
In some cases, you may want to retrofit an existing actuator with a new one. Moreover, you may also be considering replacing just the control unit to allow for either more actuators or more input devices, to be connected (i.e. remote controls and Bluetooth-enabled devices). Or alternatively, you may be looking for a combination of both.
It is crucial to understand the specifications of the device or control unit that needs replacing to ensure similar specifications of new devices. This is to make sure the speed of actuation is correct, as well as other important variables such as the force (full load and no-load) and the required voltage. If the power requirements are too high, you run the risk of the actuator’s motor burning out or if the power requirements are too low, the linear actuator will stall.
The above statements indicate that the retrofitting of a new actuator device or control unit is a task that requires careful consideration and assessment. Furthermore, a common question is whether an existing controller would work with a different actuator or vice versa. The application of these devices within the medical industry (e.g. an adjustable bed linear actuator) can be investigated to illustrate the answers to these proposed questions.
Firstly, to understand the use of a hospital bed actuator, one needs to know how they operate. A DC motor is usually used and is attached to a lead screw. A shaft is attached to this lead screw and everything is enclosed to protect the moving parts from dust or water ingress. When a voltage is applied to the terminals of the DC motor, the lead screw rotates, and the attached shaft extends. When the polarity of the voltage is switched around, the shaft retracts.
An electric actuator for an adjustable bed in a hospital is, therefore, a common use-case. These bed lift actuators can apply a force and move the bed in a variety of ways by using two or more. The bed can be divided into three segments; one-bed actuator inclines the head side of the bed, another shift the center segment while the third controls the foot-end of the bed. Moreover, another two actuators can be used to pivot the entire bed into an inclined or declined position (illustrated below).
In order to control the precise positioning of the actuators, a bed actuator remote is usually attached to the control unit. The control unit receives an input signal from the remote when a button is pressed. Upon receiving this signal, the control unit sends a voltage to the actuator to operate it. The control unit cuts the voltage to the actuator when the remotes button is released.
Progressive Automations provide a wide variety of linear actuator options and so choosing the right one for a replacement of a bed actuator would come down to the specifications that are required. For example, the PA-03 linear actuator has a force of 200lbs to 600lbs, providing a wide range for use on a medical bed. However, if more power is needed, the PA-17 heavy-duty linear actuator has a force of 850lbs to 2000lbs (may require a higher amp rating control box). The force and stroke of these linear actuators can be adjusted accordingly to match the requirements for retrofitting an existing actuator.
In terms of the control unit, Progressive Automations have the PA-20, PA-22 and PA-24, all of which have an individual wired remote control, perfect for a medical bed control unit replacement. The PA-20 is a single channel controller, the PA-22 is a 2-channel controller, and the PA-24 is a 4-channel controller. All models are rated at an input voltage 110VAC, allowing them to be connected to a wall plug. The output voltage is 12VDC and a current rating of 10.5A.
When replacing a medical bed with a new control box, the hospital bed actuator wiring will be the same for most 3rd party models since all an actuator needs is two cable connections (+V and -V). However, the wiring will be different based on whether you are using a power supply or a controller box that can perform an AC to DC conversion. For the latter, an AC voltage is fed directly into the controller box – the convenience of opting for a Progressive Automations control box.
If wiring a remote to the control box, ensure you look at the user guide to see which input pins have been allocated for input devices. Thankfully, Progressive Automations wired remote can be connected easily to its control box channel. If the connector does not match the input port, an adapter may be needed or some handy soldering skills to ensure all signal wires get to the right pin.
We have taken you through the various considerations when implementing a new actuator into your current system. The key take-away point is that most linear actuators and control units are interchangeable and retrofittable, as seen with medical care bed linear actuators. It is crucial to read the user manual of any new equipment that is purchased so that cables are wired or connected to the right ports on a control unit (i.e. avoid connecting a signal port directly to a linear actuator or an input device, such as a remote, to a DC voltage port).