tractor wire loader - Forestry Commission

INFORMATION NOTE
ODW 9.05
TECHNICAL DEVELOPMENT BRANCH
TRACTOR WIRE LOADER
Introduction
This Information Note is one of a series derived from a
Technical Development Branch (TDB) Outdoor Workshop
(ODW). It is produced as a guide to part of a harvesting
system suitable for use in small scale broadleaved
woodlands. ODWs are a TDB initiative designed to offer
practical advice to practical people through presentation,
demonstration and user guidance. The ODW programme
will involve repeating trials and introducing new systems
around Great Britain, so that a wide range of sites,
systems and practitioners can be included.
Information has been gathered from equipment and
method trials based at a single location. This information
therefore must be taken as indicative only. Variation
could be expected for other operations where factors
such as terrain, crop specification, product specification,
operating distances or operator efficiency differ.
• Caddy line operation of the winch allows the operator
to follow the load as it is extracted from the wood,
from a safe position.
The System
• Unloading is done by the use of a lifting bar and winch
boom.
The tractor wire loader system (Figure 1) is based on an
agricultural tractor (65 hp/4WD) fitted with an 'A' frame,
pto-driven winch and loading arm. A timber trailer is
attached to the draw bar of the tractor. The operator pulls
out the winch rope and skid cone to the produce. He then
operates the winch, using a caddy line attached to the
winch, to pull the produce out of the wood. The boom
attached to the ‘A’frame allows the operator to lift and
position the load on the trailer.
A 1998 case study (Table 1, Table 2 and Table 3) gave
an output for the extraction system of 0.76 m³/shr. This
was based on an average winching distance of 10 m and
a total extraction distance of 150 m. Skid loads averaged
0.085 m³ with a mean tractor load of 1.1 m³ achieved.
Costs including felling varied between £24.64/m³ at full
costing to £ 8.43/m³ if costed on a marginal basis.
Various costing options may be used. The highest (A)
assumes all machines and equipment are purchased new
and all labour charged. The intermediate costing (B)
assumes machinery and equipment has been purchased
second hand and all labour is charged. The lowest
costing (C) assumes that certain elements, such as
capital cost of the tractor and tractor operator are not
charged.
The system has the following attributes:
• Low capital cost.
• No excessive lifting of products - all lifting done by the
winch/boom. Safe and ergonomic.
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Figure 1
System Layout
Key
A:
Tractor/wire
winch
loader
B:
Timber trailer
C:
Winch line and skid
cone
D:
Produce
E:
Operator with caddy
line
Table 1
Case Study: Site and Crop Characteristics
Soil
Free draining clay loam over shale. Depth to 200
cm+
Species
Vegetation
Well developed herb layer with sporadic bramble,
shrub layer and some regen
Form
Terrain
Slope 15% - 45% with occasional steep snap
falling to a level area adjacent to a stream
Thinning volume
(m³/ha)
Access
Loosely metalled farm tracks running up/down hill
on either side of wood. Roughly surfaced track in
upper wood. Unsurfaced narrow track in lower
wood.
Average tree (m³)
2
MB. syc/ash/beech
oak
Age(yrs)
Regen130 yrs
Some good stems, but generally poor,
squirrel damage.
Average of 50 across site
0.113
Average
Piece
(m³)
0.024
Table 2
Case Study: System Description and Costings
Item
Specification
Capital Cost
(£)
Cost
(£/hr)
(A=Full, B=Intermediate, C=Marginal)
A
B
C
22 000
4.82
1.87
0.50
2 500
0.39
0.39
0.39
Tractor
MF 265, 4x4
Wire
loader
'A' framed Star Wire Loader, with optional
hydraulic swinging boom.
Trailer
Nyvan single axle double wheeled trailer.
Adjustable bed and bolster pins.
Operator
£64.00/day on 8 hour day
-------
8.00
8.00
----
Felling
Man £8.00/hr. Saw £1.00/hr
-------
9.00
9.00
9.00
22.21
19.26
9.89
Total
Table 3
Case Study: Outputs and Unit Costs
Cost (£/m³)
Study Area
Output
(m³/shr)
A
B
C
Felling
1.24
7.26
7.26
7.26
Extraction
0.76
17.38
13.50
1.17
24.64
20.76
8.43
Total System Cost
shr = Standard Hour (Includes allowances of 17% for Personal Needs and Rest, and 16% for
Other Work such as refuelling). All outputs are for skilled and accustomed operators.
• The fellers were inexperienced in the system. This
meant that the presentation was not ideal. Many piles
had produce as bearers or contained too few/many
pieces for optimum working.
Comments on Trial Performance
A simple and effective ergonomically designed system for
extraction of timber using a tractor mounted winch and
trailer. The use of the wire loader greatly reduces the
manual handling of loading and unloading timber.
• Brash left in piles on, or in front of stacks slowed
chokering.
Outputs for this system were reduced due to the following
factors:
Presentation of produce at c. 45°to the rack, on bearers,
helps with chokering and extraction.
• The local market required 2.3 m billets. This length
was shorter than the optimum 3 m to 4 m for the
system.
Although this is a relatively simple system, only persons
with correct training and relevant experience should
undertake this work.
• The shape of the billets was poor. Bent material
prevented good stacking on the trailer and
consequently the unloading mechanism could not
perform properly.
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Acknowledgements
Associated TDB Publications
Information from ODWs will be published by the Forestry
Commission. Associated publications available now are:
Thanks are expressed to:
•
•
• Report 03/95 Evaluation of Tractor Based Wire
Loader Forwarder
• Technical Note 4/97 Wire Loader Horse Forwarder
Sir Henry Studholme for use of the site.
Tony Appleby, Llysfasi College.
Technical Development Branch
Equipment Supplier
Develops, evaluates and promotes safe
and efficient equipment and methods of
work, maintains output information and
provides advice on forest operations.
Fuelwood Harvesting Ltd
Claywood
Beausale
Warwick
CV35 7NX
Tel:Fax: 01926 484673
Forest Research
Technical Development Branch
Ae Village
Dumfries
DG1 1QB
Tel:
01387 860264
Fax:
01387 860386
e-mail: tdb.ae@forestry.gsi.gov.uk
Please telephone for current prices
Crown Copyright 2002
1400A/2/02
9.05
This Report is published to advise Forestry Commission staff but for information is made available to the forest industry. It is not
intended as an endorsement or approval by the Forestry Commission of any product or service to the exclusion of others which
may be available.
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