Toomey Earthmovers 4000B, Original Instructions Manual

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4000B USER HANDBOOK
Page 34
Reverse this procedure to uncouple the scraper from the tractor. Note that there may be residual
pressure in the hydraulic circuits when uncoupling and to have an approved container handy to
capture any hydraulic oil which may spill during this process.
5.2 Loading
The method for loading a towed scraper is rather different from that of a self-propelled scraper.
The operator takes shallower cuts (10-15cm) over a greater distance. Thanks to the cutting edge
angle and greater loading speed an optimum mount profile develops allowing a greater carrying
capacity.
Two important factors in efficient loading of a towed scraper are:
1. Loading Speed
2. Cutting depth
When the scraper loads the material forms a mound in the bowl. This mound builds until it
reaches the angle of repose for that material (red lines). Once the mound exceeds this height the
material starts to roll down the mound (yellow lines). The side walls have wear skids attached
with enough free board that this behavior is considered. It will allow the material to mound up
and fill the scraper. Once the scraper is full the apron can be closed and the scraper lifted
trapping the material in the scraper.
A coordination between raising the cutting edges and closing the apron will result in a minimum
amount of material left from being drawn into the scraper. This takes practice and the operators
will gain a feel for this as their experience grows.
The diagram below shows and approximation of the material flow.
Figure 5.1 Loading Material Flow