ACELA 6X6 WITH SLRV EXPEDITION BOX NEW BUILD

martinf

Member
what is the purpose of the gate in the back? It looks like it reads max load 575lbs. Is it a platform to access the cabinets and the spare wheels?
 

poohbearusvi

Well-known member
The gate drops down to form a platform to carry bicycles and/or a motorcycle. The whole rear (tires, boxes and platform) goes up and down to ground level. The 575 lbs is the maximum load I can put on the rear lift.
 

Alloy

Well-known member
Another week of electrical work and we should be done with that part. Graphics will be done later in the week. Right now it’s scheduled to be loaded on a RORO ship March 30th to the US. Here is a shot of the rear of the rig. If I do say so myself, this is one beautiful rear end!

View attachment 643546
Might consider some reflective tape on the sides/back.
 

poohbearusvi

Well-known member
Might consider some reflective tape on the sides/back.
Both sides will get three red/amber reflector lights. In the rear, in addition to the standard tail lights are two lights at the top of the box. There are also a row of amber lights on the cab. I think this will be sufficient.
 

poohbearusvi

Well-known member
I was trying to estimate how well my rig will perform in sand. My rig will weight approximately 31,000 lbs fully loaded. I looked up the footprint of my tires on sand and the chart read 220 square inches each. Times 6 tires equals 1320 square inch footprint. (That’s at highway tire pressure, not aired down.) Divide by the weight and we get 23.5 pounds per square inch. As a comparison, I looked up another chart and got these numbers for comparison.
Human on snowshoes: 0.5 psi
M1 Abrams tank: 15 psi
Adult horse: 25 psi
Passenger car: 30 psi
Adult elephant: 35 psi
Road racing bicycle: 90 psi
Stiletto heels: 471 psi
So, based on pure numbers, it should “float” reasonably well. Won’t know the ‘real world’ experience until later.
 
Arr you sure about that 220 sq in? Michelin 395/85R20 XZLs are ~144 at full road pressure. Michelin have tables that basically recommend minimum of 33% road pressure for extreme situations, 40% for “normal” sand and mud. With speed limitations of course.
Michelin publications that I have show footprint increases naturally with decreased pressure, but it’s not 1/P. More like 1/P^^0.8.
And a strong personal recommendation: if you are going to run low pressures fit internal beadlocks if you don’t already have them. Does your CTIS work properly?
As a very rough approximation ground pressure ~ psi. When you think about the simple force vectors it becomes obvious. It is incorrect to the degree that the tire isn’t perfectly flexible however. But even a perfectly rigid wheel will sink into a soft surface till area x psi = weight.
 

poohbearusvi

Well-known member
Arr you sure about that 220 sq in? Michelin 395/85R20 XZLs are ~144 at full road pressure. Michelin have tables that basically recommend minimum of 33% road pressure for extreme situations, 40% for “normal” sand and mud. With speed limitations of course.
Michelin publications that I have show footprint increases naturally with decreased pressure, but it’s not 1/P. More like 1/P^^0.8.
And a strong personal recommendation: if you are going to run low pressures fit internal beadlocks if you don’t already have them. Does your CTIS work properly?
As a very rough approximation ground pressure ~ psi. When you think about the simple force vectors it becomes obvious. It is incorrect to the degree that the tire isn’t perfectly flexible however. But even a perfectly rigid wheel will sink into a soft surface till area x psi = weight.

I have the Goodyear 395/85R20 MV/T G tires. Their chart shows 220 sq in per tire for sand, 174 sq in per tire for cross country and 144 sq in for highway. The CTIS worked when it left Acela. Have not seen the chassis in a year so can‘t comment on it now. Here is the chart I got the info from:
0B33980D-CAA1-45F6-A8F0-82FBB1C581AE.jpeg
 
Those figures are almost identical to Michelin’s. You can see footprint only goes up by 1.5 even when psi goes down by factor 2.5 (40%) to 3 (33%). But that doesn’t take into account the huge sidewall bulge at 33% which counts in mud and soft sand. And is why you want to stay at 60-70% in rocks.
Strongly suggest weighing truck, each end separately, full of everything, when you get it. And add 1-2000 lb for rear axle pair because you’ll keep adding stuff.
 
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