Hoerbiger-Origa rodless pneumatic cylinders are driving the automatic doors on the latest generation toilet cubicles for trains, providing easy accesses for wheelchair bound passengers.
Train operators are reassessing the design of their carriages following the enactment of the Rail Vehicle Accessibility (Amendment) Regulations 2000, which amongst other issues requires wheelchair access to toilet cubicles.
With much of the nation’s rolling stock being renewed or refurbished as the whole rail system reinvigorates itself for the 21st Century, carriage builders have turned to suppliers like Jones Garrard Ltd of
One of Jones Garrard’s most popular concepts has been to produce toilet facilities as a complete stand-alone module that can be virtually dropped into place during new-build or refurbishment work. The carriage builders are thus saved considerable engineering work, and the module is designed for efficient maintenance and repair during its 15-20 year working life expectancy.
One innovation that has proved a great success is the use of a curved door, as this gives a wider opening and makes wheelchair access far easier. Powering the door for push button opening is achieved pneumatically, using a system developed by Hoerbiger-Origa that is every bit as innovative as the Jones-Garrard stand-alone module idea.
“When we initially developed the curved door actuating system, we were presented with a particular problem faced by all system installers, in that the universal access toilets are generally a retrofit / refurbishment to existing carriages, which are required under European guidelines,” recalls Ian Jones who leads Hoerbiger-Origa’s involvement in the project.
“The 'above ceiling' area is generally filled with various services (air supplies, air conditioning, electric cable looms, water supplies, control equipment etc.), leaving little space to house an actuator system for retrofitted curved doors.”
Traditionally, a rod type cylinder with clevis mountings would be used to provide this type of curved motion, but the space constraints could not accommodate this approach. The rodless cylinder solution requires, by comparison, a very small operating envelope and is easily installed - a simple 6-bolt operation.
The Hoerbiger-Origa system is based on a standard 25mm bore 950mm stroke rodless cylinder driving through a fairly simple crank arm to create the circular arc motion required by the door. The cylinder is mounted so that its stainless steel sliding seal is on a side face so that dust and dirt do not collect on it over the years and lead to premature failure. Hoerbiger-Origa also includes the curved guide rail and door hanger within its system; again these elements are engineered for ease of assembly and demounting.
The rodless concept provides further benefits in regard to controllability and operating performance, as Ian Jones explains: “having equal forces in both directions, a small diameter actuator may be used. Low friction characteristics enable a smooth slow speed operation (without stick-slip) and allow the system to be operated at a low pressure of 3 bar - a further safety consideration. Additionally the actuator is fitted with extended end of stroke cushioning to provide an extremely smooth, shock-free deceleration at the end of stroke.”
Compressed air is provided from the trains’ own ring main, via an isolating filter-regulator set to 3 bar. This acts as a safety device for emergency situations, cleans the air before use and has a soft start function so that the door never moves sufficiently fast to cause injury or even surprise. Door actuation time is specified as 5sec +/- 1 sec, and in the event that it meets an obstruction the door will fail safe to its fully open position. Door locking is automatic while the toilet is occupied and this also illuminates a remote engaged sign.
Compressed air is also used for the vacuum flushing system of the toilet, for air conditioning and for the hand drier. Jones & Garrard has made the compartment completely self-contained by giving it an integral effluent tank, and ensured ease of installation into a train carriage by reducing on-site engineering to tightening location bolts and making air, electrical, water connections.