USDA Forest Service Gravel Bags for Packstock

8/8/2019 USDA Forest Service Gravel Bags for Packstock

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Gravel Bags for PackstockUnited StatesDepartment ofAgriculture

Forest Service

Technology &DevelopmentProgram

2300-Recreation

June 19959523-2840-MTDC


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The contents of the publication are not to be used for advertising, publication, or promotion

purposes. The Forest Service, United States Department of Agriculture, has developed t

information for the guidance of its employees, its contractors, and its cooperating Federal and Sta

agencies, and is not responsible for the interpretation or use of this information by anyone except

own employees. The use of trade, firm, or corporation names in this publication is for the informati

and convenience of the reader, and does not consti tute an endorsement by the Department of a

product or service to the exclusion of others that may be suitable.

The Forest Service is a diverse organization committed to equal opportunity in employment a

program delivery. USDA prohibits discrimination on the basis of race, color, national origin, se

religion, age, disability, political affiliation, and familial status. Persons believing they have be

discriminated against should contact the Secretary, U.S. Department of Agriculture, Washingto

D.C. 20250; or call (202) 720-7327 (voice); or (202) 720-1127 (TDD).

Gravel Bags for Packstoc

Brian VachowskiProject Leader

Technology & Development Program

Missoula, Montana 59801

5E52A59Gravel Bags for Packstock

June 1995


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Introduction _____________________________________ 1

Gravel Bag Designs ______________________________ 2

Fruit Picking Bags _______________________________ 3

Testing _________________________________________ 4

Gravel Bag Test Results___________________________ 5

Recommended Design ____________________________ 6

Gravel Hauling Panniers __________________________ 6

Sources ________________________________________ 6

Fabrication Plans ________________________________ 7

Contents

Technical Assistance:

Maggie Brinks, Missoula, Montana

Ivan Carper, W allowa, Oregon

Mike Dolfay, W enatchee, W ashington

Brenda Holland, MTDC

George Jackson, M TDC

Patt i Johnston, Lew is and Clark N ational Forest

Jim Kautz, MTDC

Ray M ills, L ewis and Clark N ational Forest

Taylor Orr, Gallatin National Forest

Tony Petrilli, Northern Region Smokejumper

Professional W ilderness Out fitt ers Association

Sara Lustgraaf, MTDC

Acknowledgment

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A

fabric bag for hauling gravel or

fill material with packstock is

available for Forest Service use.

Replacement fill material is often

needed for trail work, especially for

turnpike construction and tread

maintenance. Using packstock to haul

gravel or other fill material is practical

when motorized equipment is

impractical or not allowed.

The Missoula Technology andDevelopment Center (MTDC) was

asked to develop plans, and fabricate

and test fabric bags that could be

mounted on packsaddles. MTDC

worked from a design developed in the

1970s by retired Wallowa-Whitman

National Forest (R-6) employee Ivan

Carper. Missoula smokejumper Tony

Petrilli fabricated the bags for MTDC in

1994 and they were tested on a

partnership turnpike construction

project on the Rocky Mountain Ranger

District of the Lewis and Clark National

Forest (R-1) that same year. MTDC

also tested and evaluated some bags

that closely followed the original Carper

design built by the Professional

Wilderness Outfitters Association

(PWOA), and some off-the-shelf fruitpicking bags.

Included in this report are test results,

recommendations, a design pattern,

and some alternatives.

Introduction

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Heavy canvas and liberal use of leather and rivets forreinforcement around a steel hoop make up the basic designdeveloped by Ivan Carper. MTDC modified the design inseveral ways (Figure 1). Overall dimensions were kept thesame as the original, but 16-ounce (455-gram) coated nylonCordurawas used instead of canvas. MTDC did not useleather or rivets, but relied instead on sewn seams, whichare stronger. MTDC also used tubular nylon instead ofmanila rope for the release cord. The bags were rigged with

short chains and a snap clip to fit a decker saddle. Withminor modifications, the bags could be rigged for a sawbuckpacksaddle.

Partners in the testing and work project, the ProfessionalWilderness Outfitters Association, also fabricated somegravel bags using the basic Carper design. Theirs featuredtruck tarp fabric instead of canvas, manila release ropes,and rivets instead of sewn seams (Figure 2).

Figure 1.Gravel bag design features sewn seams around a steel

hoop. Release strap was changed slightly in final design.

Figure 2.This design is similar to the first, but has riveted seams

and truck tarp fabric. Bags were filled one bucket at a time.Gloves should have been worn.

Gravel Bag Designs

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Based on a report from Mike Dolfay on the WenatcheeNational Forest (R-6) that trail contractor Pete Harvill hadbeen successfully using inexpensive, off-the-shelf fruitpicking bags to haul gravel with his string, we included twodifferent sets of these bags in the test. These were Wells &Wade #80 Super picking bag, and Citrus Bag with RopeHook. These bags (Figure 3), while admittedly not designedto haul gravel on the side of a mule, readily fit a deckersaddle with no modification. Instead of being released by

jerking a knot, the loadhad to be released bygetting close to theanimal and lifting theloaded bag of gravelenough to lift the hookoff the side of the bag.

The hoop at the top ofthe bag was smallerand not as strong asthe steel hoops on theother designs.

Figure 3.Fruit picking bags require lifting the load to release therope clips.

Fruit Picking Bags

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For 8 days in June, 1994, up to 24head of mules packed gravel for a 3/4-mile (1.2-kilometer) stretch of newturnpike construction on the South ForkSun Trail No. 202. The packstockbelonged to members of PWOA. Theyalso provided workers at the gravelsource to work alongside the ForestService crew.

Each bag was tested by carrying abouteight loads per day for 8 days (64 trips).The gravel was hauled from a riverbottom gravel bar, up a hillapproximately 1/2 mile (.3 kilometer) tothe turnpike construction site.

Both Carper design bags were loadedwith about 160 pounds (72 kilograms)per bag, for a total load of 320 pounds(144 kilograms) per mule. The

outfitters believed the mules couldhandle that load for short distances, butabout 120 pounds (54 kilograms) perbag would be better for longer hauls. Itwas easy to overload the animals. Infact, the initial loads weighed 200pounds (90 kilograms) per bag untilthey were better calibrated.

Because of their smaller dimensionsand lighter construction, the fruit pickingbags could hold only about 80 pounds(36 kilograms) of gravel per bag.

Each mule string was led through thegravel pit area, with workers on each

side filling bags a bucket at a time. Thebags were quiet, although the metalbuckets were not. When all the mulesin the string were loaded, they were ledto the turnpike. Two workers were

stationed there, one to hold the muleand the other to unload it one side at atime. The packstring was separatedduring unloading. This proved to be themost difficult procedure, since themules varied in temperament and somewere quite contentious.

Because of the difficulty of positioningsome of the mules exactly where thegravel was needed, the ability to directthe flow of gravel from the bag bypulling the rope on the bottom was veryuseful (Figure 4). Also, by lifting up onthe rope, the flow of gravel could behalted and redirected to a slightly

different spot.

In all cases, the empty bags were leftmounted on the packsaddles, tied andadjusted, ready for the next load.

Figure 4.Bags allow directing the flow of material under or away from the pack animal.

Testing

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Table 1 compares test results of the two versions of Ivan Carpers design and the fruit picking bags. The MTDC bag proved tobe most efficient. Fruit picking bags would be adequate for lightweight jobs.

Table 1.Packstock Gravel Bag Test Results

Wells & Wade #80 Superpicking bag;

Citrus bag with rope hoop; Treated canvas; Lightweight metal hoop; Sewn seams

$22-$27 per bag, plus freight

Approximately 80 pounds(36 kilograms) per bag

Economical; Able to direct flow somewhat; Lightweight 2-3 pounds(.9-1.4 kilograms) each;

Quiet; Easy to roll up and pack

away

Metal rim not heavy enough,tendency to collapse;

Small opening made loadingharder;

Limited capacity; Had to get close to animal

and lift load to release hooks

Top side of one bag rippedout, but repairable

Bags not designed for gravelbut serviceable for light dutyuse, especially when costand quick availability aremost important

18-ounce (510 gram)polyester with PVC resintruck tarp;

Riveted seams; Manila release rope; 3/16-inch (4.76 millimeter)

steel hoop

No current manufacturersmall lot fabrication costsabout $80 per bag

Average 160 pounds (72kilograms) per bag;

Easy to overload

Direct flow up to 4 feet (1.2meters);

Lightweight 5.5 pounds (2.5kilograms);

Quiet; Easy to roll up and pack

Chain rattled when bag wasempty

Two tops came undone atrivets, but repairable

1/4-inch manila ropes woreout...replaced with 3/8-inch

(9.5 millimeter) manila; Fabric tore on one bag, butrepairable

Fabric held up well and costsless than nylon Cordura,so it is recommended forfinal design;

Riveted seams not as strongas sewn seams

16-ounce (455 gram) nylonCordurasewn seams;

Tubular nylon release strap; 3/16-inch (4.76 millimeter)steel hoop

No current manufacturersmall lot fabrication costsabout $80 per bag

Average 160 pounds (72kilograms) per bag;

Easy to overload

Direct flow up to 4 feet (1.2meters);

Lightweight 5.5 pounds (2.5kilograms);

Quiet; Easy to roll up and pack; Tubular nylon worked well

Chain rattled when bag wasempty;

Tubular nylon sometimescaught in chain (fixed in finaldesign)

Stitching in bottom of onebag wore out, but repairable

Final strapping designmodified so it will not catchon chain;

Nylon Corduraheld upwell but more expensive thanpolyester with PVC resintruck tarp;

Sewn construction strongerthan riveting

DESIGN THAT WAS TESTEDPOINTS

CONSIDERED"Carper" Design - MTDC Fabricated "Carper" Design - PWOA Fabricated Fruit Picking Bags

Construction

Approximate Cost

Load Carried

Best Features

Limitations

Observed Wear

Comments

Gravel Bag Test Results

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Ivan Carpers design as modified byMTDC is the recommended bag.Fabrication plans are included in thisreport. The design is sized to theoriginal specifications, but is modified torequire sewn seams and a slightlydifferent load release rigging. Althoughthe bags originally fabricated by MTDCused 16-ounce (455-gram) nylonCordura, the recommended planscall for 18-ounce (510-gram) polyesterwith PVC resin truck tarp material, aless costly yet durable fabric that heldup well in the bags made by theoutfitters. Corduracould also besubstituted if desired.

The fruit picking bags could beconsidered serviceable for light dutyuse, especially when initial cost outlayand quick availability of an off-the-shelfproduct are the most importantconsiderations. The bags do not quiteutilize the full load capability of packmules, and are unlikely to stand up tosustained heavy-duty use. They maybe a good alternative to hauling gravelin buckets or wheelbarrows in manyinstances.

Fruit Picking Bags:The Wells & Wadebags are manufactured by:

Superior Fruit CompanyPO Box 3444Wenatchee, WA 98807-3444Phone: (509) 662-5881or (509) 662-6065

Aluminum Gravel Panniers:

Wyoming Outdoor Industries, Inc.1231 13th St.Cody, WY 82414Phone: (307) 527-6449

Dave Fish Saddlery

1706 Brooks St.Missoula, MT 59801Phone: (406) 543-8566

For additional copies of this report orfurther information on bag fabricators,contact:

Brian VachowskiUSDA Forest Service, MTDC5785 Hwy. 10 WestMissoula, MT 59808-9361Phone: (406) 329-3935

Hard-sided panniers were not evaluatedin the tests. Often fitted with hingeddrop doors, these have been around formany years. Often gravel would bindor break the hinges, the boxes arebulky, and most designs provided noway to direct the gravel on its way outof the box.

Improved aluminum gravel panniers,featuring a sliding, rather than a hingeddoor, are available from WyomingOutdoor Industries, Inc. Similar panniershave been fabricated by other saddleshops. We did not evaluate hard-sidedaluminum panniers, but based on

reports from some who have usedthem, the panniers work well and arevery sturdy. They are bulkier, noisy(should be lined with some type offabric to cut down on noise), and aremore expensive than fabric gravelbags. The aluminum panniersavailable from Wyoming OutdoorIndustries, Inc., currently cost $395 perset of two, not including rigging.Discounts are available when morethan one set is ordered.

SourcesRecommendedDesign

Gravel HaulingPanniers

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Fabrication Plans

The schematic MTDC gravel bag pattern on page 9 shows the general layout. Plan dimensions could vary slightly based on fabricused. Fabricate a prototype before mass producing. The steel hoop should be fabricated first.

33-1/2"

Placement

of weld.

12

"

1. Steel bar is 1-1/4" x 45-1/2" x 3/16".

2. From the center point of the bar,measure 6" out on each side and make90bends on both. Now round the freeends together and weld.

3. Weld the chain links to the hoop.A carabiner or metal double snap clipcan be used to connect the chains toeach other. Decker saddles require 9"of chain on each side, while sawbuck

saddles require 20" per side.

STEEL HOOP DETAIL

SEWING INSTRUCTIONS

1. Fold material with wrong sidestogether, and match 1" side dots with theback side 2" dots and stitch (Figure A).

2. Check to make sure the material will

fit snugly around the metal hoop, thenremove hoop.

A

R

W

B

Stitch line

from Step 1.

R

3. False Fell Seam: Fold the 2" sidearound the 1" side (Figure B). Tuck by

folding it again and stitching as shown.The second stitch line must be startedfrom one end to the halfway point. Clipthread and finish stitch line from theother end.

R = right side of material, and W = wrong side

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SEWING INSTRUCTIONS, continued

Cut here.

4-1/2"

CR

4. The hoop end willbe double-folded. Toreduce bulk, cut4-1/2" of false fellseam from the hoopend (Figure C).

F

R

Cut-away detail

Stitch line in Step 6.W

Stitch line in

Step 10.

Fabricfold

Steelbar

9. Fold fabric aroundthe hoop. Hoop edgeshould be on the8-1/2" fold line dots.

10. To attach thehoop inside the bag,stitch close to thefold edge on theinside of the hoop(Figure F).

R

4-1/2

"

5-1/2

"

W

Cut-away detail

D5. At the hoop end,fold at the 5-1/2" foldline.

6. Stitch completelyaround on the 4-1/2"stitch line (Figure D).

G

R

W

Stitch made

in Step 10.

Lock stitch made

in Step 11.Stitch made

in Step 6.

Steelbar

Cut-away detail

11. To secure thehoop, stitch over thestitch line created inStep 6, reinforcing itsince the machinewill not sewcompletely into thecorners. Lockstitches (Figure G).

E

1-1/4"

1/2"

R

R

7. Cut rectangularholes for hoop chainlinks. Use a hot-knifeif material isCordura,and burnthrough both layers(Figure E).

8. Insert the hoopand pull the chainlinks up through theholes.

H

R R

Matchdiamonds

D-ring

12. Bottom D-ring:Webbing 1-1/2" x10". Use 3-point,running 'W' stitch(Figure H).

13. Bottom support:Material 17-1/2" x

2-1/2" with 1" seamtape on all foursides.

14. Attach tapedpiece on three sides(two long sides andone short side).

15. Insert 1" x 16"steel or aluminumstrip. Sew open endshut.

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Stitch Line

Fold Line

Fold Line

( Right side of material)

Stitch

Line

Selvage Edge

Hoop Edge

19-1/2"

Holes to be madein Step 7.

Placement points forbottom D-ring in Figure H.

28-1/4"

29-1/2"

49"

2"

These vertical rows of dots match.(The left row should be marked on

the wrong side of the fabric).

1"

24-3/4"

32-1/2"

23-1/4"

15"

8-1/4"

2"

12"

22"

32"

42"

2-1/2"

4-1/2"

4-1/2"

5-

1/2"

8-1/2"

49"

8-3/4"

18-1/4"

MATERIAL LAYOUT

M A T E R I A L S L I S T

49" x 49", 18-ounce polyester with PVC resin, (PVC "truck tarp")*17-1/2" x 2-1/2" 18-ounce polyester with PVC resin, (PVC "truck tarp")*1" x 40" seam tape1-1/2" x 10" nylon webbing3/4" x 3' tubular nylon3/4" x 9' tubular nylon

*Alternative material: 16-ounce coated nylon Cordura

1-1/2" D-ring1-1/4" x 16" x 3/16" steel, or 1/4" aluminum flat stock1-1/4" x 45-1/2" x 3/16" steel bar1 medium-size carabiner or metal snap clip2 each 9" chains for decker; or2 each 20" chains for sawbuck

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Notes

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Documents

USDA Forest Service Gravel Bags for Packstock