Which winch?

dwr

Anybody know how to calculate how powerful a winch is needed to pull a Tab 400 (or any other RV) up a 6% slope?

qhumberd

Found this calculator. Says the winch pull is only 305 lbs. Another source says that winch capacity is twice the GVWR of what you are winching.

Bet some engineers here can help

Grumpy_G

The 305 lbs number is under ideal conditions with no rolling resistance. Tires and the surface add to the pulling power needed. Which sorta dovetails into the "twice the GVWR" rule that is used in serious off-road circles: When a vehicle is stuck in deep mud it requires a lot of pulling power to get it out. 

I'd say a 2000 lbs winch should do on a paved surface. Would be good to know what the actual scenario is, is the winch mounted to a vehicle or to a building which also determines 12V or 120V. 

dwr

Thank you, both. The surface is partly paved, partly crushed gravel ... so not too bad.  Mostly, I've not been able to figure out how the slope affects the winch requirements. . .  I've been thinking of mounting a portable winch to a fixed plate on a post at the end of my trailer pad, keeping open the option of mounting another winch mount on my Tabby.  But my primary use is for a tricky parking problem at home.

dwr

 Final notes for those with similar issues.

1. The slope on the steep part of my drive is actually more steep than I indicated: 6 degrees or a 10% grade.

2.  I found a discussion on line with a useful chart for calculating my winch needs.

Weight Capacity Changes On Inclined Pulling Using A 10,000 LB. Winch To Pull a 5,000 LB. Vehicle % Percent Incline   Pulling Capacity (10,000 LB. Winch) 0% (level surface) 10,000 (100%) 5% (3 degree) 6,670 (66.7%) 10% (6 degree) 5,020 (50.2%) 20% (11 degree) 3,400 (34%) 30% (17 degree) 2,610 (26.1%) 50% (26 degree) 1,860 (18.6%) 70% (35 degree) 1,530 (15.3%) 100% (45 degree) 1,290 (12.9%)

My full loaded Tabby comes in between 4,200-4,300 lbs.  If I throw in a fudge factor and allow for up to 5,000 lbs, it will be too heavy by 20 lbs to pull up a 6°-10% grade with a 10,000 lbs capacity winch.  That's ok but, in a surfeit of caution, I’m going to get a 12,000 lbs winch.     

Specifically, I’m looking at a Smittybuilt 98612 XRC 12K Gen 3 Winch.

https://smile.amazon.com/Smittybilt-98612-Winch/dp/B07B3QGNNS/ref=sr_1_2?dchild=1&keywords=smittybilt+98612+xrc+12k+gen+3+winch&qid=1631127946&sr=8-2

 

 

Grumpy_G

The winch will certainly do the job but it's absolute overkill. The typical offroad vehicle winches are rated based on pulling a dead weight on a level surface. For dead weight the table is correct but the T@b is a rolling load which requires much less pulling power. That's why a single person can easily move a 320 on a flat, hard surface. This article on e-trailer has a table for rolling loads and inclines: https://www.etrailer.com/faq-electric-winch.aspx Keep in mind that the winch ratings are for the first layer of the drum and more layers lead to less pulling power. 

In the end it's your money and do whatever you feel comfortable with.