Flats,


If your axles are spread in Canada, you only get 20,000 for both, not each. This is for the Western Provinces, I'm not sure about Ontario and Eastward.

From the British Columbia Commercial Transport Regulations:

7.17

(2) A person must not, without an overload permit, drive or operate on a highway a vehicle or combination of vehicles having a group of axles within a spacing of 8 m or less if the group of axles carries, along any 8 m axle length, the gross weight indicated in column 2 of the table opposite the distance between the centres of the first and last axle of the group indicated in column 1:
[TABLE="class: tablestyle1"]
[TR]
[TD="colspan: 3, align: center"]Column 1[/TD]
[TD="align: center"]Column 2[/TD]
[/TR]
[TR]
[TD="colspan: 3, align: center"]Distance between the centres of

the first axle and last axle of any

group of axles of a vehicle or

combination of vehicles
[/TD]
[TD="align: center"]Maximum

gross weight,

group of axles
[/TD]
[/TR]
[TR]
[TD="colspan: 2, align: right"]less than[/TD]
[TD="align: right"]1.00 m[/TD]
[TD="align: right"]9 100 kg[/TD]
[/TR]
[TR]
[TD]1.00 m[/TD]
[TD="align: center"]up to but not including[/TD]
[TD="align: right"]1.20 m[/TD]
[TD="align: right"]16 500 kg[/TD]
[/TR]
[TR]
[TD]1.20 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]1.90 m[/TD]
[TD="align: right"]17 000 kg[/TD]
[/TR]
[TR]
[TD]1.90 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]2.30 m[/TD]
[TD="align: right"]18 000 kg[/TD]
[/TR]
[TR]
[TD]2.30 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]2.60 m[/TD]
[TD="align: right"]19 000 kg[/TD]
[/TR]
[TR]
[TD]2.60 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]3.00 m[/TD]
[TD="align: right"]20 000 kg[/TD]
[/TR]
[TR]
[TD]3.00 m
[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]3.40 m[/TD]
[TD="align: right"]21 000 kg
[/TD]
[/TR]
[TR]
[TD]3.40 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]3.80 m[/TD]
[TD="align: right"]22 000 kg[/TD]
[/TR]
[TR]
[TD]3.80 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]4.20 m[/TD]
[TD="align: right"]23 000 kg[/TD]
[/TR]
[TR]
[TD]4.20 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]4.60 m[/TD]
[TD="align: right"]24 000 kg[/TD]
[/TR]
[TR]
[TD]4.60 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]5.00 m[/TD]
[TD="align: right"]25 000 kg[/TD]
[/TR]
[TR]
[TD]5.00 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]5.30 m[/TD]
[TD="align: right"]26 000 kg[/TD]
[/TR]
[TR]
[TD]5.30 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]5.70 m[/TD]
[TD="align: right"]27 000 kg[/TD]
[/TR]
[TR]
[TD]5.70 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]6.10 m[/TD]
[TD="align: right"]28 000 kg[/TD]
[/TR]
[TR]
[TD]6.10 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]6.50 m[/TD]
[TD="align: right"]29 000 kg[/TD]
[/TR]
[TR]
[TD]6.50 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]6.90 m[/TD]
[TD="align: right"]30 000 kg[/TD]
[/TR]
[TR]
[TD]6.90 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]7.20 m[/TD]
[TD="align: right"]31 000 kg[/TD]
[/TR]
[TR]
[TD]7.20 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]7.60 m[/TD]
[TD="align: right"]32 000 kg[/TD]
[/TR]
[TR]
[TD]7.60 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"]8.00 m[/TD]
[TD="align: right"]33 000 kg[/TD]
[/TR]
[TR]
[TD]8.00 m[/TD]
[TD="align: center"]"[/TD]
[TD="align: right"][/TD]
[TD="align: right"]34 000 kg[/TD]
[/TR]
[/TABLE]

[en. B.C. Reg. 95/2006, s. 3.]

I made the text for what should correlate to our 10' 1" spread axle trailers bold and red.

3m to 3.4m = 9.84ft to 11.15ft.

21,000kg = 46,297.02lbs

Looks to me like the regs are about the same there as they are here. Actually, if the tires and axles are rated for it, up there you can carry more on a 10' 1" spread than you can down here.
 
From the British Columbia Commercial Transport Regulations:



I made the text for what should correlate to our 10' 1" spread axle trailers bold and red.

3m to 3.4m = 9.84ft to 11.15ft.

21,000kg = 46,297.02lbs

Looks to me like the regs are about the same there as they are here. Actually, if the tires and axles are rated for it, up there you can carry more on a 10' 1" spread than you can down here.
Track Width
Semi-trailers and full trailers manufactured after
December 31, 1993, must have a track width
(outside of tire to outside of tire) of not less than
2.5 m nor more than 2.6 m. (Container chassis
trailers are exempt.)
Weight
a) truck tractor steering axle, maximum 5,500 kg,
except a self-loading truck tractor or bed truck
b) tridem drive truck tractor steering axle,
maximum 7,300 kg, except permanently
mounted equipment will be allowed 9,100 kg
c) single axle equipped with dual tires, maximum
9,100 kg
d) tandem axle, maximum 17,000 kg
e) tridem axle on semi-trailer and trailer, minimum
2.4 m to maximum 3.7 m axle spread, legal
24,000 kg
f) in c) and d) above any axle cannot exceed
9,100 kg or any 2 adjacent axles cannot
exceed 17,000 kg
g) maximum single tire weight 3,000 kg, except
steering axle of straight truck is allowed
maximum single 9,100 kg, maximum twin
steer 17,000 kg (subject to tire size 100 kg/cm
tire width and rated tire capacity)
Note: The maximum allowable weight on a tridem axle for
T.A.C. lowbed semi-trailers, granted by an overload permit,
is 28,000 kg (2.4 to 3.0 m axle spread), or 29,000 kg (over
3.0 to 3.7 m axle spread).
2. Axle Weight – Spacing of
(Non-Compliant Commercial
Vehicles)
The number and spacing of axles to carry maximum
legal weights are shown below.
7
Table 1 – Maximum Weight
Column 1 Column 2
Distance between the centres of the Maximum gross
first axle and last axle of any group of axles weight of
of a vehicle or combination of vehicles axle group
less than 1.00 m ...........................................9,100 kg
1.00 m up to but not including 1.20 m ........16,500 kg
1.20 m up to but not including 1.90 m ........17,000 kg
1.90 m up to but not including 2.30 m ........18,000 kg
2.30 m up to but not including 2.60 m ........19,000 kg
2.60 m up to but not including 3.00 m ........20,000 kg
3.00 m up to but not including 3.40 m ........21,000 kg
3.40 m up to but not including 3.80 m ........22,000 kg
3.80 m up to but not including 4.20 m ........23,000 kg
4.20 m up to but not including 4.60 m ........24,000 kg
4.60 m up to but not including 5.00 m ........25,000 kg
5.00 m up to but not including 5.30 m ........26,000 kg
5.30 m up to but not including 5.70 m ........27,000 kg
5.70 m up to but not including 6.10 m ........28,000 kg
6.10 m up to but not including 6.50 m ........29,000 kg
6.50 m up to but not including 6.90 m ........30,000 kg
6.90 m up to but not including 7.20 m ........31,000 kg
7.20 m up to but not including 7.60 m ........32,000 kg
7.60 m up to but not including 8.00 m ........33,000 kg
8.00 m ........................................................34,000 kg
Maximum allowable spacing for tandem axles in B.C.
is 185 cm unless the first and/or last is a steering
axle or one that articulates in the manner of a
steering axle.
Spread-axle tandems that have a spacing greater
than 185 cm (6 ft.) but not more than 307 cm (10 ft. 1
in.) are allowed on a semi trailer if their combined
axle weight is not more than 9,100 kg (20,000 lbs.).
Tandem axles of this type are measured as a unit
and the weight of both axles together must not be
more than 9100 kg (20,000 lbs.).

If we look at the portion of the regulation you left out, we see that 20,000 is the limit for spread-axle tandems that have a spacing of greater than 6 ', but not more than 10'1".
 
Is it true that dump valves on spread axles are used similar to that of a tri axle dump valve on a tractor so that the rear axles pivot better during turns? I always just thought the dump valve was to help you unhook a tractor from the trailer. I was never aware of this because at my last company, we took turns spreading the gravel out in the parking lot from where people dragged the axle at a 90 degree pivot.
 
Is it true that dump valves on spread axles are used similar to that of a tri axle dump valve on a tractor so that the rear axles pivot better during turns? I always just thought the dump valve was to help you unhook a tractor from the trailer. I was never aware of this because at my last company, we took turns spreading the gravel out in the parking lot from where people dragged the axle at a 90 degree pivot.
A dump valve only releases air pressure. On a trailer (without a lift axle), it releases the pressure from the air bags which takes the pressure off of an axle. The axle will still drag around a turn, but with only its own weight pushing down, it doesn't dig in very much.

Most tri axles (and some trailers) have lift axles. A lift axle requires 2 dump valves and 2 separate sets of air bags all working together.

To lift an axle, one dump valve releases the pressure on the weight supporting bags and the lift bags inflate and pick up the axle.

To lower the axle, the other dump valve releases the pressure on the lift bags, and the weight supporting bags inflate to help support the trailer.

Edit - I haven't worked on a lift axle for a long time. They might use just one complicated valve to do everything these days.
 
One feature some spread axle trailers have is an auto dump on the back axle. When the sensor detects twist, it dumps the air in the rear axle. A spread axle's worst enemy is a driver turning too fast. You can eat the tires off those things pretty quick.
 
One feature some spread axle trailers have is an auto dump on the back axle. When the sensor detects twist, it dumps the air in the rear axle. A spread axle's worst enemy is a driver turning too fast. You can eat the tires off those things pretty quick.

If this is true then its the dumbest invention I've ever heard of! I can see many broken trailers in the future...LOL
 
If this is true then its the dumbest invention I've ever heard of! I can see many broken trailers in the future...LOL

Yep. Cuz if it malfunctions & you're rolling down the road with 40,000 lbs on a single axle cuz the rear deflated, or if it fails to deflate & the guy doesn't know it & it rips the tires off the rims. Or if the guy is an idiot and thinks that ALL spread axle trailers are like that & pulls one that doesn't have the auto-dump thingy on it.
 
Yep. Cuz if it malfunctions & you're rolling down the road with 40,000 lbs on a single axle cuz the rear deflated, or if it fails to deflate & the guy doesn't know it & it rips the tires off the rims. Or if the guy is an idiot and thinks that ALL spread axle trailers are like that & pulls one that doesn't have the auto-dump thingy on it.

Contrary to popular belief dump valves do more harm than good. Mostly due to the fact that they aren't used properly or they are over used. East Mfg would void a warranty if there was a dump valve hooked up on one of their trailers...
 

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