Calculations

The following options are found under menu Calculations in the main window.

 

Diminishing Load

Clearance Calculations

Chassis Height

Turning Radius Legal

Turning Solo

Turning Operations

Start PERF

 

 

 

 

 

 

 

 

Diminishing Load (2003)               (Main Window - Calculations)

In the Diminishing Load calculation the vehicle is unloaded from the back. The vehicle must have a body. Both rigid truck, tractor and trailer can be calculated. In the tractor case the trailer is unloaded.

The calculation assumes uniformly spread load. If the payload position of the body is not in the centre, the calculation assumes it is in the centre. However, if a bulkhead is specified on the body, the calculation takes that into account. Thus only the loaded body length is used.

On the horizontal axis is percentage load which means the percentage of the original load area that still is loaded. On the vertical axis there is load. The curves tells you the load on the front (king pin on semi trailer) and rear axis respectively. At percentage load 80 for example, 20% of the load and load area has been unloaded. The load on the front axle increases to a maximum which is displayed at the top.

 

Clearance Calculations                     (Main Window - Calculations)

Calculates the clearance between the truck and the trailer and some other clearances, see below. The result depends on which trailer is chosen. The same principle apply for the clearance between trailers. Exchange "truck" below with "first trailer". The case of two semi-trailers (b-train) is a bit special, see below.

Steered Axle Drawbar Trailer

Calculates the clearance at level between the corners when they are the closest (trailer turned). The program retrieves the

 

Centre Axle Drawbar Trailer

Calculates the clearance between the corner of the truck and the front wall of the trailer at 6 and 0 degrees inclination when they are the closest (trailer turned). The program retrieves the

 

Semi Trailer

Calculates the clearance between the cab or a crane on the tractor and the corner of the trailer at 6 degrees inclination when they are the closest (trailer turned). The critical point on

In the case of two semi-trailers (b-train), the program calculates clearance between the trailers if the first trailer has a body on it. If you place something behind the body on the first trailer (for example a crane), it is not taken into account in the clearance calculation.
 

Other Clearances

In all cases you also get the cab to crane clearance if you have a crane close to the cab. It is calculated from the cab rear wall (withour air intake) to the leftmost point on the crane.

If you have put a fridge unit on the body, the program gives the clearance between the tilted cab and the fridge. The fridge dimensions is given in the Crane etc window. The radius of the tilted cab is formed by the rear top edge of the cab. Air intake etc is not included.

In the case of a semi trailer you also get:

 

 
                                                                       

Chassis Height                                             (Main Window - Calculations)

Distance from frame top to wheel top over the first drive axle when

Chassis height at actual load is interpolated from the unladen and max. laden heights.

On leaf suspension, the values are fetched from chassis drawings. That means that chassis height data may not be available for all specifications. In that case WIS shows a warning.
 
 

 

Turning Radius Legal                              (Main Window - Calculations)

Calculates the inner turning radius when the front corner of the cab follows an outer radius of 12.5m (EU-circle). In the case of an articulated combination it may be the front corner of the trailer instead that follows the outer radius depending on which is critical. Between walls means that all parts of the combination are inside the radiuses. It is only a geometrical calculation, thus no influence of tyres, load, type of ground etc are taken into account.

Rear overhang outswing is the distance that the rear corner swings out from the line made by the side of the truck just before turning starts. The program retrieves the truck corner from the body width and the rearmost point on the truck which can be the chassis, a body or an object in Crane etc. If the truck has no body, 2550mm is used.

In the case of a centre axle trailer (and in professional mode) the angle between the truck and trailer in the turn is shown (when the combination is going straight, the angle is zero).

The coordinate of the cab front corner can in professional mode be changed in Bumper Corner.

This calculation is the same as Circle 12.5m in the SVEP program.

 

 

Turning Solo                                                                     (Main Window - Calculations)

Calculates the minimum outer turning radius for a solo truck when it turns with full wheel angle. Between walls means that all parts of the truck are inside the turn radius. Between Kerbs means that the wheels are inside the turn radius.

WIS takes into account that air suspension and some tyres limit the steering on FL6 E-medium.

WIS takes into account that 24" tyres limit the steering.

WIS does not take into account that 22.5" spoke wheels limit the steering.

Rear overhang outswing is the distance that the rear corner swings out from the line made by the side of the truck just before turning starts. The program retrieves the truck corner from the body width and the rearmost point on the truck which can be the chassis, a body or an object in Crane etc. If the truck has no body, 2550mm is used.

Both calculations are only geometrical, thus no influence of tyre forces/slip, load, type of ground etc are taken into account. Use the results with caution, add about 10% margin.

The coordinate of the cab front corner can in professional mode be changed in Bumper Corner.

This calculation is the same as Minimum Turning Radius in the  SVEP program.

 

 

Turning Operations                                                 (Main Window - Calculations)

Starts the SVEP program and sends all needed dimensions on your specification to it.

 

 

SVEP                                                                                    (Main Window - Calculations - Turning Operations)

A separate program for turning calculations. All needed dimensions on your specification are sent to SVEP when you start it by clicking menu Turning Operations  under Calculations. In SVEP you have a variety of turning calculations to choose from. The program works with turning centres specified by the turn wheelbases of the truck and trailer (turn wheelbase is in most cases the same as the theoretical wheelbase see main window). The calculations are only geometrical, thus no influence of tyres, load, type of ground etc are taken into account. For help on SVEP, start SVEP and select Help under menu Help.

In professional mode it is possible to edit the dimensions inside SVEP.

How to use a DXF drawing in SVEP. Only in professional mode. To import it to the Citrix server, use the clipboard as described in Open Text File.

 

 

Start PERF                                                                        (Main Window - Calculations)

Starts PERF-program (Performance calculations) and exports data from WIS to PERF. The interface between the programs will be fully operational when a new version of PERF is released. The idea is that WIS knows data that PERF needs. Another reason is that you can specify the truck in WIS and then go over to PERF. PERF needs to be installed and started once before the connection works.