Manco Rail has well and truly carved a name for itself as an industry leader in the supply of hi-rail electrification construction and maintenance equipment.
An important part of such plant are train straddles, which when used can be valuable aids for the rail industry.
Manco Rail managing director Bryan Black outlines some of the major considerations and features of the current generation of straddles.
- Operator location:
“Current straddles are generally radio remote-controlled, allowing a great deal of flexibility for operator location, particularly in tunnel utilisation, where operator location on the straddle can restrict working heights,” Black said.
“A good example is when the straddle is operating on a wagon or trailer consist running rails, two operators can be deployed; one at the loading point and the second at the unloading phase,” he said.
“This ensures operators are in ideal locations for each function.”
- Travel speeds:
Historically, the use of straddles in rail construction has been limited because of their inability to operate at reasonable speed in comparison to other traditional plant, such as front loaders, bobcats, and the like.
However, with the advancement in electronics and the use of load sense hydraulics, a multitude of speed options can be incorporated in the design.
“For example, locating the straddle to the work face in an unloaded mode can be executed at high speed (up to 20kph), but in laying sleepers and track, a slow walking pace is normally all that is required to ensure positional accuracy,” he said.
- Multifunctionality:
Black said a significant benefit of a straddle over the use of typical construction plant is the simultaneous function capability provided.
“For example, in a sleeper laying operation, travel, height and sleeper spread can all be executed at one time,” he said.
“Sleepers are frequently transported tightly packed, and the ability to spread them to the final exact spacing offers good productivity gains over other methods.”
- Straddle dimensions:
The ability to have automatic adjustment of the straddle height and width provides significant benefits for utilisation.
For transporting on road or rail to the work site, the straddle can be full retracted/ extended and lowered/raised hydraulically by remote control.
“For example, a typical requirement in tunnel applications can be the need to reduce the straddle width to clear obstacles such as platforms, walkways, electric/ signalling control boxes,etc, and yet to be able to expand and raise for operation,” Black said.
“Another consideration can be dimensional restrictions when deploying the straddle for overseas projects.”
Black said there were other points to note about straddles:
- Steering systems: Interfacing laser directional steering with the remote control provides a highly accurate method of automated sleeper laying and track alignment.
- Safety: Today’s straddles always incorporate a high degree of operational safety features, such as extensive working light packages, automatic fire suppression, emergency stops on all corners, failsafe braking with auto stop guarding during direction travel, extensive audio and visual alarms for travel, lift and steer functions.
- Attachments: The modern straddle includes a wide array of attachments to improve utilisation. From expanding sleeper grabs, to general lifting of materials by sling loads. Even an under-slung rail threader can be used.
- Safe working loads: The use of hydraulic cylinders and multi sheave blocks enables high loads to be achieved, without impeding on the available lift heights. Multi-winch units can be difficult for coordinating rope speeds and are best to be only used when the intention is to vary the angle of the suspended load for some particular reason.
- Straddle drive options: Using the straddle over a series of wagons or trailers in consist can be highly functional. The straddle in such applications is fitted with anti-derailment hooks, and the rail wheel profile sits well into the wagon/trailer track which is normally a deep U section. When operating on solid rubber wheels, all-wheel drive with enclosed wheel motors incorporating failsafe oil immersed cone brakes on all wheels is the most common. Crab steering is a far more functional method to having one fixed axle and a one steering axle.
- Undulating ground: The modern straddle design uses a fixed cross beam at one end and an osculating robust joint at the other. This ensures that equal load displacement occurs at all times.
“In summary, there is no question that provided there is extensive discussion between the end user and the straddle manufacturer, today’s straddles can be a very useful piece of plant,” Black said.
“There needs to be a clear understanding of the operational requirements, loads, travel speeds and productivity expectations between both sides.”
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