Technology
3RCI+ Height and Slew Limit Technology
The 3RCI+ System Has Been Developed In The UK For Network Rail For The Assistance In Safe Working Under The Wire And Beside Live Adjacent Tracks. Version 8 of the technology has been in existence now for 7 years with no recorded failures.
The basic functions of the system are:
- Height Limits - Virtual Ceiling
- Slew Limits
- Virtual Walls
- Load Exceedance whilst in Hirail Mode
Included in this leaflet are:
- A brief overview of the 3RCI+ installation
- GKD 3RCI+ Quick Start Guide
There are a few differences between the machines used in the UK and those used here in NZ.
The most obvious is that the UK more commonly uses Wheeled excavators and we use Tracked excavators. This has created a few challenges for us, but nothing we have not been able to overcome.
There has been a lot of work put into this installation and adapting this technology to be used safely and effectively here in NZ.
The hope would be in the future that GKD in the UK could produce a product that was specifically designed for use by us here in NZ.
3RCI+ Overview and Installation
Gravity sensors are carefully calibrated to know the shape of the particular part of the excavator they are attached to. They then all work together to understand the overall shape of the excavator. By communicating together, they will always know what the highest point on the machine is and what is the furthest point of the machine.
This allows us to create ‘walls’ and ‘ceilings’.
Two sets of Gravity sensors are used for safety. Both sensors must agree with one another. If they do not or one sensor fails, then the system will stop you from operating.
Gravity sensors
Gravity sensors are mounted on the following parts of the machine:
- Main Body of the Excavator
- Main Boom
- Stick (Dipper Boom)
- Tilting Head/Bucket
Along with providing vital information to the system regarding height and width, the Gravity sensors on the main body of the excavator also provide a live reading inside the cab of the ‘Gradient’ and ‘Cant’ of the track.
Proximity sensors
In conjunction with Gravity sensors, we also use Proximity sensors:
- These firstly provide a ‘Zero’ marker on the slew ring, for when the body is dead straight with the track frame and pointing forwards in relation to the direction of travel.
- They also count the teeth in the slew ring, this tells the system which way the operator is slewing and shows the precise position of the body of the excavator in relation to the track frame. Giving you a ‘degree’ reading inside the cab, as in between 0-360 degrees.
- This is important for use with the Load Exceedance side of the technology.
- This also allows us to set ‘Slew’ limits rather than just setting ‘Walls’. We could set a slew limit of say 45 degrees but still maintain full reach of the machine or we could set a wall, measured from track centre, to have full slew but restrict our reach. Or we can use both together.
GKD 3RCI+ Quick Start Guide
The system has a touch screen mounted inside the cab of the excavator.
This screen can be folded back against the window for better visibility for the operator.
Everything is controlled from this screen.
When a wall or slew limit has been set, and the key has been switched to the locked position, a blue indicator will be displayed above the front windscreen of the machine. The key can then be removed and given to the Mobile Plant Controller or the Electrical Safety Observer. Permission is then required from either of these people to alter any of the limits that have been set. Once the limits have been set, and the key removed, these limits will remain with the machine no matter how many times you switch the machine on or off.
The system operates in either ‘Road’ mode or ‘Rail’ mode:
- Road mode being when the machine is operating on its tracks.
- Rail mode being when the machine is operating in a Hirail capacity.
The system automatically switches between these modes when the hirail gear is raised or lowered. The hirail gear also has motion cuts. If you are working on your tracks and you are at your ceiling limit the system prevents you from operating your hirail gear preventing you from breaking through your ceiling by raising the machine up on its rail gear. Pressure sensors are mounted on the main lift rams. These measure load capacity and assist in providing vital information for the load exceedance technology that is used when the machine is in Rail mode.
Additional hydraulic valving has been installed to allow us more control over the machine. This valving provides us with:
- Motion Cuts
- Slow downs
The Motion Cuts are on the following:
- Boom
- Stick
- Bucket
- Slew
- Hirail
Slow downs have been put on the following functions:
- Boom Up
- Stick Out
- Slew Left
- Slew Right
We have also set two working slew speeds. Normal ‘fast’ speed of the slew is maintained when no slew limits or walls are set.
The moment a slew limit, wall or even a ceiling is set, the machine automatically selects a secondary ‘slower’ slew speed. Ensuring a smooth operation when we reach our slow down and then stops/limits.
5 electronic modules are mounted under the floor of the operator’s cab.
The system also has 2 audible alarms to provide various safety warnings:
- One is mounted in the front under the floor alongside the electronic modules.
- The other is mounted to the rear, in the right side engine compartment.
The system also has a built in Watchdog:
- If a fault is detected in the system or one of the sensors, the watchdog will automatically restrict Boom and Slew operation to prevent accidental breaching of a limit.
If there was some failure of the system while working on track and the watchdog has locked out movement, the system has a built in ‘Key Override’:
- The Key Override is mounted in the left rear compartment. Directly below the battery isolation switch.
- This can be accessed by unscrewing the front plate and turning the key.
- This will override any lock outs and allow us to clear the machine from the track.
