CAT Scales; Why/How/What they tell you.
A thanks to Rustic Eagle (Bob) for contributing to this thread
(Definitions for the acronyms below can be found HERE)
To really know if your TV/TT (or HTT, etc.) combination is within specified weight limits and that our WDH is adjusted correctly, a visit to a CAT scale is the best way to accomplish this.
A WDH is designed to remove weight from a TV’s rear axle, and then distribute it to the TV’s front axle and TT axles. Many of us use the standard method of adjusting a WDH by measuring the TV’s fenders (fender to ground) when unhitched, and then hitched with WDH spring bars engaged. Measuring the TV fender distances gets us in the “ball park”, but a CAT scale can confirm that the proper amount of weight has been transferred. This is critical in maintaining the TV’s original front suspension steering and handling characteristics.
Before heading to a CAT scale, grab a yard stick in the event that you can’t reach the CAT scale “call button”. Confirm that TV fuel is full, and TV/TT combination is under “loaded” weight conditions. If you “normally” travel with fresh water in your TT tank, put some in.
Upon arriving at the CAT scale location, first see the attended before heading to the scale. Advise him/her that you would like to weigh your TV/TT combination and that you will be making three (3) independent trips across the scale. First weigh is usually around $7-$9, remaining two should be cheaper. Provide the attendant with an identifying name that you will use while at the scale.
During each separate weigh-in, driver/passengers should remain in the TV:
1st Weigh: TV only (unhitch TT in open parking area).
2nd Weigh: TV/TT hitched and WDH spring bars engaged.
3rd Weigh: TV/TT hitched with WDH spring bars released, but hanging (attached).
Note: “Sometimes” you can remain on the scale after the 2nd weigh and make the WDH adjustment in preparation for the 3rd weigh. Ask the attendant if this is ok.
1st Weigh: As you approach the scale for your 1st weigh (TV only) you will see three separate weighing platforms, place your TV’s front axle on one platform and rear axle on another. Push the “call button” from your TV, or get out and push it but return to your TV. The attendant will respond, then advise him who you are…., and he will advise you when the weighing process is complete. Drive off the scale and hitch your TT back up.
2nd Weigh: The 2nd weigh will be your TV/TT combination with WDH spring bars engaged. Locate the TV front axle on the first platform, TV rear axle on the second platform, and the TT axles on the third platform. Repeat “call button” process. Drive off scale.
3rd Weigh: For your 3rd weigh, dis-engage your WDH spring bars but leave them hanging (attached). Drive back to the scale and stage the TV/TT axles as in the 2nd weigh. Repeat the “call button” process. Drive off the scale, re-engaged your WDH spring bars…, and then go back to the attended to obtain your three separate CAT weight certificates.
Referencing your three CAT weight certificates:
Loaded TT weight: (2nd weigh TV/TT gross weight) minus (1st weigh TV gross weight).
Loaded Tongue weight: (3rd weigh TV axle weights) minus (1st weigh TV gross weight). Tongue weight should be 10% -15% of loaded TT weight (13%-15% on longer TT’s).
Loaded TV weight: 1st weigh gross weight.
Loaded TV/TT weight: 2nd weigh gross weight.
TT GVWR: Confirm that the “Loaded TT weight” doesn't exceed the TT GVWR.
TV GVWR: (2nd weigh steering axle weight) plus (2nd weigh drive axle weight) sum total should be less than the TV GVWR.
TV Axle limits: The 2nd weigh TV axle weights shouldn’t exceed the GAWR (F/R) limits noted on your TV’s driver’s door.
TV GCWR: The 2nd weigh gross weight should be less than specified TV GCWR.
TV Front Axle weight transfer: Most TV manufactures recommend that when using a WDH that the TV’s front axle weight be returned to it’s “unhitched” loaded axle weight; so the 2nd weigh steering axle weight should be the same as the 1st weigh steering axle weight. If the 2nd weigh steering axle weight is plus/minus 50 lbs (weight variable I use), then the WDH is adjusted correctly. If the weight difference is larger than 50 lbs either way, re-adjustment of the WDH should be considered. If the weight difference approaches/exceeds 100 lbs, re-adjustment of the WDH should be preformed.
Note: On full size GM Trucks & SUV’s allowing the 2nd weigh TV front axle weight to exceed the 1st weigh TV front axle weight may force the front suspension against the upper suspension stop. Always refer to the Towing section in your TV’s Owners Manual for specific specifications when using a WDH.
Other: The previous weight data can be used to confirm that the TV’s receiver and WDH are sized adequately to handle the “loaded weights” confirmed by the CAT scale.
CAT scale locations:
CAT Scale
Bob
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