GNER contracted EWSR now DB Schenker Rail to
provide strategic rescue services for its HST fleet operating out of
London. The Class 67 locomotive was selected for the job because it is a
high-speed diesel locomotive. However, the Class 67 has a combination
coupler that does not interface with the coupler carried on the HST.
So, ESG were commissioned to design, test and deliver a suitable
adapter to connect the two locomotives.
Due to the restricted side clearance of the draw
hook on the swinghead autocoupler, the current adapter (that fits a
standard locomotive drawhook) did not fit. Initial design ideas
investigated ways of modifying this adapter but were quickly replaced
with one that interfaced with the knuckle coupler of the Class 66/67.
Drawings were created on AutoCAD, and stresses calculated using MathCAD
software. The main design constraints were; ensuring the component
withstands the rated strength without any permanent set; is of low
weight (for man-handling); ease of installation and manufacture; and
low cost. Material selection formed a vital part in this process, and a
high-alloy aluminium was finally selected.
There was some initial testing of a lightly modified
drawhook adapter, as currently used on the HST, but this proved to be
difficult to fit effectively and, more importantly, was unstable in
buffer mode. It was clear that the best solution was to interface with
the autocoupler on the 66/67 and a prototype was made and subject to
controlled field testing using an HST trainset and a Class 67 (checking
installation/fit, low speed curving, static pull etc). the coupler was
then subject to destructive proof testing on a tensile rig.
The coupler performed very well in all tests and met
the proof tensile test requirement, it eventually failed when subject
to an offset (5°) tensile load just above the rated value.
A second prototype was made and subject to yet more
rigorous field testing, hauling a HST set up the East Coast Main Line
to London and back. During the test, the loco speed and traction amps
were monitored to ensure the coupler received the full tractive effort
of the locomotive. After the test, critical dimensions were rechecked
to ensure there was no permanent set. The test was also an opportunity
to gauge the opinion of ground staff into the ease of fit and
installation of the adapter coupler.
Although, the coupler met the test criteria, it was
decided to strengthen the component around the area of failure (the
second pin joint) and the material section was increased around this
feature.
The coupler was fitted with more robust locating
chains and supplied with short extension hoses, following experience
gained on test and input from GNER ground staff.
Surface finish and chamfering details were added to
the drawing, to improve the look and ease of physically handling the
coupler.
ESG managed the production of over 20 adapter
couplers, fitted safety labels, attached ancillary components and made
up the extension hoses, so that a complete kit could be presented to the
client. Spare parts and maintenance information (such as NDT) were
also developed and supplied as part of the contract. ESG also managed
the delivery and transportation logistics to ensure the product was
supplied to the clients agreed programme and location.
- Selection of materials to meet stringent strength and weight (man-handling) requirements
- Full technical support for design and production units
- Extensive testing in laboratory and on full HST rakes, out on the track
- Comprehensive 'one-stop shop' solution for the client
- Design compliant to latest Railway Group Standards and legislative regulations
- Design to meet stringent cost and turn around timescales
- Material selection
- Laboratory and on- track testing
- Project Management
- Client liaison
- Risk assessment
- Technical documentation (spares and maintenance)