INSTRUCTIONS FOR USE OF SHERLINE SCALE HOW SHERLINE SCALE WORKS The Sherline scale uses a hydraulic principle to convert weight into a direct reading on a hydraulic pressure gauge. The reading in pounds per square inch is read as weight in pounds. Any hydraulic pressure gauge that reads in PSI can be substituted for the one supplied should you wish to measure different ranges of weight. RECOMMENDED GAUGE RANGES For maximum accuracy, use a gauge that will put your expected final measurement in about the middle of the gauge's range. (For example: for tongue weights of about 1000 lb. use a gauge that reads to 2000 lb.) The reason for this is that pressure gauges of this type are accurate to within about 2% in the middle ranges, but accuracy decreases at extreme low or high readings. To provide a gauge a few percent more accurate would increase the cost by 10 times or more. The supplied gauge was chosen as the most cost effective solution to providing a result that is sufficiently accurate for trailer weighing purposes. (The Sherline scale is not intended to be used for trade; i.e., items priced by weight.) On Sherline gauges, the PSI reading equals the weight in pounds. CHANGING GAUGES Should you wish to use your Sherline scale to measure a different range of weights, simply unscrew this gauge and replace it with another gauge which also reads in PSI. It should have a 1/4" pipe thread fitting. Be sure to tip the body of the Sherline scale so the hole is up so no hydraulic fluid is lost when the gauge is removed. When replacing the gauge, push the cylinder down slightly to raise the fluid level right to the top of the hole so that no air enters the system. If fluid is lost, replace with any good quality low viscosity oil, such as a 20 weight motor oil. Use Teflon tape on the pipe threads when reinstalling the gauge to prevent leakage. NOTE: Gauges with different ranges of measurement are available from Sherline. Contact us for more information should you have a specific requirement that is not fulfilled by the gauge you now own. PLACEMENT OF YOUR SHERLINE SCALE The most accurate measurement of tongue weight is achieved by measuring right where the hitch actually rests on the ball. An extension is provided that screws into the top of the cylinder so that you may support the trailer hitch in this manner. Always measure the hitch weight with the trailer level (trailer wheels blocked to prevent movement) and the hitch at the approximate height it will be when installed on the tow vehicle. Support the trailer tongue with the tongue jack. Using very strong and secure blocks, block the Sherline scale into position under the hitch. (If you have a hydraulic floor jack, you can make things easier by simply placing the Sherline scale on the jack and jacking it into position.) Raise the tongue jack until the full weight of the hitch is on the Sherline scale and read the weight in pounds directly from the gauge. NOTE FOR MATH PROS AND PERFECTIONISTS... For the ultimate in accuracy, note the actual difference in weights and calculate the ratio by dividing the full hitch weight by the weight at the tongue jack. Example: Weight at hitch = 950 lb. Weight at jack = 1000 lb. 950 ÷ 1000 = .95 Future measurements at the jack multiplied by .95 will yield the exact weight at the hitch itself. For 5th wheel trailers, the Sherline scale can be blocked to the proper height directly behind the hitch on the bed of the truck. With the trailer supported by the trailer jack, move the truck forward until the kingpin is directly over the scale. Lower it into position with the trailer jack until the full weight of the trailer is on the scale. Note: Because of the large variety of available 5th wheel hitch designs, some ingenuity may be required on your part to safely support the kingpin on the scale. Once you are familiar with your trailer, it will be easier to measure tongue weight at the tongue jack rather than at the hitch. Once you have determined the actual tongue weight at the hitch, we recommend you take a reading at the tongue jack itself. With the hitch supported by the tow vehicle but not locked down, place the Sherline scale under the tongue jack. (A depression is provided in the top of the piston to help locate the jack leg or wheel.) Making sure the wheels of the trailer are blocked so it can't roll, crank the tongue jack until the hitch is just free of the ball and all the weight is on the scale. Compare this reading to the one taken at the hitch itself. You will probably find that it is close enough to use as the actual measurement in the future depending on the distance of the jack from the hitch. Just keep in mind the approximate ratio and add that factor to your measured figure at the jack. IN CONCLUSION I hope that by using your Sherline scale you will have a better knowledge of the factors involved in safely loading and towing your trailer. An actual measurement will give you much greater peace of mind than your best guess. I would also hope you will share your expertise and help friends to better balance their rigs with the fine equipment you now have at hand. Each of us who shares the highway is benefited by having one more safely loaded rig on the road.

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