Volvo fh Diff lock switch and axle lift switch

UK PROFESSIONAL DRIVERS FORUMS THE UK PROFESSIONAL DRIVERS FORUM (INTERACTIVE)
1

I don’t have a manual for the unit so a bit of help is needed please.

I do a bit of off road driving and need as much traction as I can get especially when its raining,
I use the diff lock and lift axle to try and put as much weight as I can over the drive axle.

So why does the diff lock switch have 2 stages and what is the difference between stage 1 and 2 ?

Also the mid lift button can be pressed and then pushed a stage further and then springs back to the first stage, can anyone expain the purpose ?

I always run at 44t with a walking floor so the load is evenly spread, sometimes the axle goes up and is clear of the ground and sometimes it is taking some of the weight ? Usually when I play around with the button.

Thanks

2

I could never figure out the diff lock but the 2nd stage on the lift axle button is to shift more weight onto the drive and off the lift for a short period of time

3

michael.d.s.:
I don’t have a manual for the unit so a bit of help is needed please.

I do a bit of off road driving and need as much traction as I can get especially when its raining,
I use the diff lock and lift axle to try and put as much weight as I can over the drive axle.

So why does the diff lock switch have 2 stages and what is the difference between stage 1 and 2 ?

Also the mid lift button can be pressed and then pushed a stage further and then springs back to the first stage, can anyone expain the purpose ?

I always run at 44t with a walking floor so the load is evenly spread, sometimes the axle goes up and is clear of the ground and sometimes it is taking some of the weight ? Usually when I play around with the button.

Thanks

1 may be lenght 2nd and 3th Axle
and 2 may be diagonal “right-left”
Normally drives that Wheel with the less Traction,on one of the 2 Drive Axles.
switch to 1 and it drives both Axle one Wheel on each. That with the less Traction.
Switch to 2 and all 4 Wheel drive

and
Yes,
On Termac usually drives left Front and right Rear Wheel if on possition 1 till cornering or slippery,then it drives where it is the easiest.

4

I had a look at the manual and it says

Automatic engagement of the differential lock (DLC — Diff Lock Control) Set the switch for the differential lock to the centre position. The differential lock is engaged automatically when the driving wheels rotate at different speeds and the speed is less than 15 km/h. The differential lock is disengaged if the speed exceeds 15 km/h or at the next gear change. When the truck is delivered from the factory, the automatic differential lock between the wheel pairs is disengaged. This can be changed in the “Automatic diff lock” menu under the main heading “Vehicle settings” in the display. Set the switch for the differential lock to the centre position.

I think the stuff in bold is for 6x4 units.
I suppose you use this when you going between good and poor grip, but if you need full diff locks then you go the the final position, with the safety catch.

5

This is copied from a table of the switch functions

Overview of the switch’s functions
Switch position 0 (upper position) No differential lock engaged.
Switch position 1 (centre position) and TCS engaged. DLC active.
Switch position 1 (centre position) and terrain- TCS engaged DLC inactive.
Switch position 1 (centre position) and TCS disengaged DLC inactive.
Switch position 2 (lower position) The differential lock is manually engaged.

6

And in case you want to know more about the TCS.

Traction Control System (TCS)
With Traction Control System (TCS), better stability and driveability is achieved. TCS automatically reduces wheel spin by reducing the engine’s driving torque. At speeds below 40 km/h the TCS also functions as an automatic differential brake and brakes the wheel that is spinning.
TCS functions The normal mode is that the TCS is active when the truck is started. The indication lamp in the switch is not on.
Engage terrain TCS in difficult driving conditions such as in sand, gravel or snow. Below is a flow for how the button is used in relation to the functions,TCS, terrain-TCS and TCS disengaged.

  • Engage terrain-TCS by a short press on the switch. The indication lamp in the switch lights.
  • Disengage TCS completely by holding in the switch for a short time. The indication lamp in the switch flashes.
    Return to the normal mode (TCS) by pressing the switch. The indication lamp in the switch is out

I’ve learned quite a bit about my truck in the last hour, loads more to these trucks than moving a wheel about a bit. :smiley: