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Design of Unpowered Railway Vehicles
Published in Simon Iwnicki, Maksym Spiryagin, Colin Cole, Tim McSweeney, Handbook of Railway Vehicle Dynamics, 2019
Anna Orlova, Roman Savushkin, Iurii (Yury) Boronenko, Kirill Kyakk, Ekaterina Rudakova, Artem Gusev, Veronika Fedorova, Nataly Tanicheva
Open body designs are used in gondola wagons with discharge hatches, solid-bottom gondola wagons and open hopper wagons, as shown in Figure 3.23. Owing to an open-top design, the upper chord of the side wall takes up compressive stress resulting from the bending of the car, for which, generally, a reinforced rectangular hollow section is used. The upper chord of the side wall also resists the load when the car is turned over during unloading on a car dumper and can also be subjected to impact loads from a grapple or excavator bucket. Owing to the open-top design, the side wall is attached to the underframe in a cantilever fashion, and the side wall posts resist the bending moment from the load lateral pressure. The largest bending torque is observed at the bottom of the posts and at the junction with crossbearers. An open-top design with internal transverse trusses is occasionally used, which receives a lateral pressure acting on the side walls and transfers forces from the side walls to the centre sill. Although such a technical solution makes it possible to reduce the body weight, it worsens unloading conditions for bulk cargo, in particular if frozen at low temperatures.
Biomass Logistics
Published in Jay J. Cheng, Biomass to Renewable Energy Processes, 2017
In a tree-length system, trees are harvested using a feller-buncher which cuts a tree using a large spinning disk saw and then lays the tree in a pile or bunch. Next, a skidder uses a large grapple to pick up the tree piles at one end and drag them to a central location at the logging site called the logging deck. Along the way, skidders may push the trees in reverse though a delimbing gate to break off the limbs and tops. If a delimbing gate is not employed, the limbs and tops will be removed either manually with a chainsaw or using a pull through delimber and loader. The loader will pick individual trees from the pile and pull them to the deck by the skidder. The loader can sort the trees according to size, perform the delimbing and topping operations, and place the trees on the truck for shipping.
What Is Intermodal Freight Transport?
Published in Lowe FCILT David, Intermodal Freight Transport, 2006
Unaccompanied articulated semi-trailers are carried on certain UK and European rail services by a method known as ‘piggyback’ transport. The semi-trailers are either lifted onto special low-height railwagons by container crane or by straddle carriers fitted with grapple arms which locate into strengthened pockets in the trailer under frame or are shunted, by a terminal tractor, onto special rail wagons with a swivelling, tilting, load-bed, which rotates and lowers to form a ramp. Neither the tractive unit nor the driver travels on the train, the unaccompanied semi-trailer being picked up from a rail terminal at the other end of the journey by another tractive unit and driver for final delivery to its destination.
Assessing productivity and cost of timber harvesting during longleaf pine ecosystem restoration
Published in International Journal of Forest Engineering, 2023
Jacob Murray, Patrick Hiesl, Donald Hagan, Robert Baldwin
We found a significant decline in the utilization rate of our knuckle-boom loader because machine operations were only observed when machines were on, and only one operator would control the feller-buncher. Therefore, if the feller-buncher was active, the skidder operator would frequently switch between loading and skidding depending on wood availability and trucking demands. This increased the idling time for the grapple skidder but was more influential on the loader. If the primary operator was operating the knuckle-boom loader, the feller-buncher was most likely not running, and the skidder operator was exclusively operating that machine. Thus, the feller-buncher experienced the least amount of idling time because if it was not in use, it was off, and the knuckle-boom loader experienced the greatest amount of idling time because it was continually in use or waiting to be used.
Comparison of modeling approaches for evaluation of machine fleets in central Sweden forest operations
Published in International Journal of Forest Engineering, 2023
Rikard Jonsson, Mikael Rönnqvist, Patrik Flisberg, Petrus Jönsson, Ola Lindroos
Technical utility (TU) is connected to a machine’s technical complexity and the maturity of its technology, and a high TU indicates a well functioning machine, which is connected with a lower cost impact. Both the harvester and the forwarder are technologically mature, and hence have high TU. The harvester is more complex than the forwarder. The harwarder is assumed to have a similar maturity of technology as the harvester and the forwarder, but also has a tilt and rotatable load carrier and quick hitch and so might be expected to have a higher TU than both because of its complexity. On the other hand, the technology for harvesting is only used until the load carrier is filled. Then, the harwarder transports its load to the roadside and unloads using a forwarder grapple. Therefore, the harvester and the harwarder were assigned the same TU (Table 1).
Productivity measurement of New Zealand forest harvesting sector using the DEA-Malmquist index
Published in International Journal of Forest Engineering, 2020
This study utilizes the Forest Growers Research (https://fgr.nz/) benchmarking database managed by the University of Canterbury, New Zealand that contains system, stand, and terrain factors on plantation forest harvesting operations in New Zealand from 2008 to date. An important uniqueness of the database is that it offers data on individual forest harvesting operations thus offering higher variability unlike aggregated data with reduced variability and potentially lower efficient frontier (Helvoigt and Adams 2009). The data were screened to remove entries with missing or invalid data/outliers. A panel data for the year-to-year analysis were obtained from the database comprising 73 DMUs (i.e. individual forest harvesting operations) per year from 2009–2018. This resulted in a total of 730 DMUs for the entire study period of 10 years from 2009–2018. While the harvest operations in New Zealand are mostly clear fell, about 62% of the harvest were ground-based while 38% were cable logging with the felling method for the operations evenly split between chainsaw (50.5%) and mechanized felling (49.5%). Extraction machines utilized in the operations include grapple skidder, cable skidder, forwarder, hauler, shovel, swing yarder, and tractor. However, grapple skidder was the most common extraction method as it accounted for 45% of all extractions for the 730 harvest entries.