Published in Agron J 100:783-784 (2008)
DOI: 10.2134/agronj2007.0359N
© 2008 American Society of Agronomy
677 S. Segoe Rd., Madison, WI 53711 USA
NOTES & UNIQUE PHENOMENA
A Swinging Stage to Continuously Level a Platform Balance for Field Use
T. L. Springer*
USDA-ARS, Southern Plains Range Research Station, 2000 18th Street, Woodward, OK 73801. All programs and services of the USDA are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, age, marital status, or handicap
* Corresponding author (Tim.Springer{at}ars.usda.gov).
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ABSTRACT
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Subsample wet weight is usually taken with a portable platform balance often times situated on the tailgate of a truck. Each time the vehicle is moved, the balance must be re-leveled, and depending on the terrain, it may have to be shimmed. A "Swinging Stage" was designed, built, and tested to determine its usefulness in weighing subsamples. The Swinging Stage was constructed from common materials and takes about an hour to build. After the parts are cut and preassembled, the support hanger can be secured to a truck's stake rack and the stage suspended from it. Next, a platform balance can be placed onto the stage and initially leveled. To test the Swinging Stage performance, the vehicle was moved several times onto varying slopes and each time the balance remained level. The Swinging Stage eliminated the time and frustration of leveling a platform balance each time the vehicle was moved.
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NOTES
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All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher.
Received for publication November 1, 2007.
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INTRODUCTION
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WHEN HARVESTING FORAGE PLOTS, a given area is often harvested and weighed in bulk. A subsample of the forage is collected, weighted, oven dried, and weighed again to determine moisture content. The sample bulk weight is usually determined using a mechanical hanging scale suspended from an overhead bar off the side of a pickup truck or forage harvester or from a tripod. The subsample wet weight is usually taken with a portable platform balance often times situated on the tailgate of a pickup truck. Each time the vehicle is moved, the platform balance has to be re-leveled, and depending on the terrain, the balance may have to be shimmed. Additionally, leveling a balance can be time consuming as well as frustrating. The ‘Swinging Stage’ (Fig. 1
) is described that will continuously level a platform balance regardless of terrain eliminating the frustration and time required for that task after an initial leveling of the balance.
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Fig. 1. The "Swinging Stage" will continuously level a platform balance regardless of the terrain. The photograph shows a vehicle parked on a slope with a level platform balance sitting on a Swinging Stage.
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CONSTRUCTION AND ASSEMBLY OF A SWINGING STAGE
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Table 1
provides a list of materials needed to construct a Swinging Stage, and an exploded view of the parts is shown in Fig. 2
. To construct the support hanger of the Swinging Stage, a piece 0.4 m (about 16 in) long is cut from the 3.8 cm by 1.5 m square steel tubing. Drill a 9.5 mm (3/8 in) hole about 2.5 cm from the end of the 0.4 m piece of steel tubing. Insert a 9.5 mm by 2.5 cm eye bolt into the hole and secure with the nut. Weld the end (opposite the eye) perpendicular to the 1.1 m square steel tubing. Note: the open end of the eye should hang down when the long arm of the support is placed into the stake rack of the truck bed. The eye should be at least 1.4 m (approximately 54 in) above the bed of the truck when the support hanger is placed in the stake rack.
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Fig. 2. Exploded view of the parts used to construct a "Swinging Stage." Refer to text for details on how to build a Swinging Stage.
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To construct the Swinging Stage, a 40 by 50 cm stage was cut from a scrap piece of 19 mm plywood. Plywood was chosen because of its durability and strength; but, other suitable materials could be used. Next, cut a piece of #12 steel jack chain 3.7 m long into four pieces, each 0.9 m in length. Each end of the 0.9 m lengths of chain should have a complete chain link. Number 12 steel jack chain was chosen because the hook of the 4.7 mm by 10.2 cm hook 
eye turnbuckle and the 38 mm dry-wall screw will fit through the last link of the chain. Chain was used because it will not stretch like rope or twine. Once the chain is cut to length, drill a 3.2 mm (1/8 in) pilot hole about 2 cm from each corner of the plywood stage along the 40 cm side. The pilot hole should keep the plywood from splitting when a dry-wall screw is screwed into the plywood. Attach each 0.9 m length of chain to the plywood stage by placing a dry-wall screw through the last link of the chain and securing to the plywood stage at the pilot holes. Next, open the snap ring and thread the eyes of the four 10.2 cm and one 20.4 cm hook and eye turnbuckles onto the snap rings.
Final assembly begins by securing the support hanger to the truck's stake rack. With the 2.5 cm eye of the eye bolt hanging over the truck bed, hang the hook of the 20.4 cm hook eye turnbuckle into the 2.5 cm eye. The attached snap ring and four 10.2 cm hook and eye turnbuckles will hang below. Next, attach the four loose ends of the 0.9 m lengths of chain to the four hooks of the 10.2 cm hook and eye turnbuckles. This will complete the construction and assembly of the Swinging Stage.
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FIELD PERFORMANCE OF THE SWINGING STAGE
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Once in the field, the Swinging Stage was assembled and a platform balance was placed onto the stage. The balance was connected to a 12 v automobile battery through an 800 W direct current (DC) to alternating current (AC) converter. The four feet of the balance were set to their minimum and the balance was leveled using the four 10.4 cm hook and eye turnbuckles. By lengthening and shortening the 10.2 cm turnbuckles the balance was leveled (bubble in the bulls eye level on the balance was centered). Each time the pickup truck was moved, a Styrofoam pillow was placed under the plywood stage to reduce excessive vibrations. When the truck was stopped, the pillow was removed and the balance was self leveling. To reduce environmental stress (excess heat) on the balance, a bath towel was used to shade it when it was not in use. Using the Swinging Stage saves us the time and frustration associated with leveling the platform balance each time the vehicle and balance are moved. When constructing a Swinging Stage, the dimensions of the support hanger, stage, chain, etc. could be changed to accommodate any size platform balance and the support hanger could be made of something other than steel or constructed in a different configuration than what is shown.
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ACKNOWLEDGMENTS
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I thank Mr. W. J. Cooper for his help with the building and testing of the Swinging Stage.
All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher.
TOP
ABSTRACT
INTRODUCTION
