Selecting the subframe and attachment. Description. Recommendations

Transcription

1 Description Description The chassis frame, subframe and reinforcement interact in order to handle all types of stresses which may arise during operation. Subframe dimensioning and design, attachment and reinforcement are determined by a number of factors such as chassis type, torsional rigidity class and duty class. Recommendations This document describes Scania's general recommendations for dimensioning and design of subframes based on current duty class, torsional rigidity class and components. Further information on subframes for tractors can be found in the document Fitting the fifth wheel. No account has been taken of any requirement for clearance for wheel movements, load handling, total vehicle level, bodywork attachment in the subframe, etc. The chassis weight should be kept as low as possible and the vehicle comfort and driving characteristics should not be impaired. 09:40-01 Issue 4 en-gb 1 (17)

2 Procedure Procedure 1. Determine the duty class. 2. Determine torsional rigidity class and identify bodywork-based recommendations. 3. Identify recommendations dependent on the components the vehicle is to be equipped with. 4. Review each recommendation category. In case of several recommendations within the same category, determine the most suitable recommendation. In general, the recommendation providing the greatest mechanical strength should be followed. Categories: Subframe Attachment in the front section of the subframe Attachment in the rear section of the subframe Reinforcement 5. Check other factors which may have an effect on the subframe bodywork design. Examples of such factors are: Wheel clearance requirements Special height requirements for the loading surface Accessibility and servicing Attachment of hydraulic cylinders in the chassis More information on duty classes, torsional rigidity classes and components can be found later on in this document. 09:40-01 Issue 4 en-gb 2 (17)

3 Duty classes Duty classes Scania vehicles are designed and built for many different operating conditions. The different operating conditions place different requirements in terms of resistance to dynamic forces. Therefore every vehicle is adapted for a specific duty class indicating the operating conditions for which the vehicle is intended. M H E Medium Heavy duty Extra heavy duty Type of road Well maintained surfaced roads Poorly maintained surfaced roads or well maintained unsurfaced roads Off-road or poorly maintained unsurfaced roads Duty class M H E More information on duty classes can be found in the document Chassis information and model designations under Chassis information. 09:40-01 Issue 4 en-gb 3 (17)

4 Torsional rigidity classes Torsional rigidity classes Bodywork is divided into the following 3 torsional rigidity classes. Torsional rigidity Type of bodywork class Torsionally flexible Tipper bodies, fixed flatbed bodies, mixer units, demountable bodies, timber superstructures, tractors Torsionally rigid Swap bodies, skiploaders, box bodies Very torsionally rigid Tank bodies, bulk bodies, slurry removal tanker bodies, concrete pump bodies Torsional rigidity class Duty class Subframe and brackets Torsionally flexible Torsionally rigid Very torsionally rigid M H E Subframe a : U-profile, 110x80x6 U-profile, 110x80x6 U-profile, 110x80x6 Attachment in the subframe's front section b : Longitudinally flexible Flexible upwards Flexible upwards and downwards Attachment in the rear section of the subframe: Rigid Semi-flexible Flexible upwards and downwards Subframe c : U-profile, 160x80x6 U-profile, 160x80x6 U-profile, 160x80x6 Attachment in the front section of the subframe b : Longitudinally flexible Flexible upwards Flexible upwards and downwards Attachment in the rear section of the subframe: Rigid Semi-flexible Flexible upwards and downwards Subframe d : U-profile, 200x80x6 U-profile, 200x80x6 U-profile, 200x80x6 Attachment in the front section of the subframe b : Longitudinally flexible Flexible upwards Flexible upwards and downwards Attachment in the rear section of the subframe: Rigid Semi-flexible Flexible upwards and downwards 09:40-01 Issue 4 en-gb 4 (17)

5 Torsional rigidity classes a. Other subframe dimensions may be used provided the profiles' surface moment of inertia is a minimum of 290 cm 4. b. When fitting a crane behind the cab, the attachment in the front section of the subframe may be rigid, whereas it must be rigid when fitting a winch. c. Other subframe dimensions may be used provided the profiles' surface moment of inertia is a minimum of 900 cm. d. Other subframe dimensions may be used provided the profiles' surface moment of inertia is a minimum of 1,200 cm 4. 09:40-01 Issue 4 en-gb 5 (17)

6 Components Components Drawbeam Towing units subject the frame to loads and affect dimensioning and reinforcement of the frame's rear overhang. 2 axle vehicle with trailer JT Subframe fitted with fixed joint on the rear overhang Subframe fitted with flexible or semi-flexible joint on the rear overhang JT 3,000 mm JT > 3,000 mm JT 1,000 mm JT > 1,000 mm Trailer Two or three axles Gross vehicle weight 20 tonnes Gross vehicle weight > 20 tonnes Additional reinforcement is normally not required Additional reinforcement is normally not required Single X-rod in chassis frame 4 axles Single X-rod in chassis frame Further information about bodywork attachments is available in the document Bodywork attachment. 09:40-01 Issue 4 en-gb 6 (17)

7 Components 2 axle vehicle with central bogie trailer JT Subframe fitted with fixed joint on the rear overhang Subframe fitted with flexible or semi-flexible joint on the rear overhang JT 1,500 mm JT > 1,500 mm JT 1,000 mm JT > 1,000 mm Central bogie trailer Bogie spacing 2,000 mm Gross vehicle weight 16 tonnes Gross vehicle weight > 16 tonnes Bogie spacing > 2,000 mm Additional reinforcement is normally not required Additional reinforcement is normally not required Single X-rod in chassis frame Single X-rod in chassis frame Further information about bodywork attachments is available in the document Bodywork attachment. 09:40-01 Issue 4 en-gb 7 (17)

8 Components 3 and 4 axle vehicles with trailer JT Subframe fitted with fixed joint on the rear overhang Subframe fitted with flexible or semi-flexible joint on the rear overhang JT 4,000 mm JT > 4,000 mm JT 2,400 mm JT > 2,400 mm JT JT 5,300 mm JT > 5,300 mm JT 3,700 mm JT > 3,700 mm Trailer or 3 axles Gross vehicle weight 36 tonnes Gross vehicle weight > 36 tonnes Additional reinforcement is normally not required Additional reinforcement is normally not required Single X-rod in chassis frame 4 axles Single X-rod in chassis frame Further information about bodywork attachments is available in the document Bodywork attachment. 09:40-01 Issue 4 en-gb 8 (17)

9 Components 3 and 4 axle vehicles with central bogie trailer JT Subframe fitted with fixed joint on the rear overhang Subframe fitted with flexible or semi-flexible joint on the rear overhang JT 2,900 mm JT > 2,900 mm JT 2,400 mm JT > 2,400 mm JT JT 4,200 mm JT > 4,200 mm JT 3,700 mm JT > 3,700 mm Central bogie trailer Bogie spacing 2,000 mm Gross vehicle weight 24 tonnes Gross vehicle weight > 24 tonnes Bogie spacing > 2,000 mm Additional reinforcement is normally not required Additional reinforcement is normally not required Single X-rod in chassis frame Single X-rod in chassis frame Further information about bodywork attachments is available in the document Bodywork attachment. 09:40-01 Issue 4 en-gb 9 (17)

10 Components Close coupling drawbeam When fitting a close coupling drawbeam, the rear overhang does not normally require any additional reinforcement. Semi or fully underslung drawbeam Drawbeams which are fully or semi underslung must be supplemented by an additional crossmember, such as an end beam. More information can be found in the document Reinforcement. 09:40-01 Issue 4 en-gb 10 (17)

11 Components Tail lift Strong tail lifts with a lifting capacity exceeding 2,000 kg place a load on the frame and affect the dimensioning, attachment and reinforcement of the subframe and chassis frame. 2 axle vehicle 3 and 4 axle vehicles 3 and 4 axle vehicles with tri-axle bogie JA (BEP-L020) 3,000 mm JA (BEP-L020) 4,000 mm JA (BEP-L020) 5,300 mm JA JA JA Tail lift Lifting capacity 2 tonnes Lifting capacity > 2 tonnes Additional reinforcement is normally not required Fixed bodywork on entire length of rear overhang and double X-rods in subframe Additional reinforcement is normally not required Fixed bodywork on entire length of rear overhang and double X-rods in subframe Additional reinforcement is normally not required Fixed bodywork on entire length of rear overhang and double X-rods in subframe 09:40-01 Issue 4 en-gb 11 (17)

12 Example of subframe dimensioning Example of subframe dimensioning Conditions The vehicle concerned has the type designation R 470 LB6x2MNA. The vehicle must be equipped with the following: Fully underslung drawbeam with a distance between the half shaft and connecting point of 2,600 mm Box body with rigid sides Tail lift with a lifting capacity of 2,300 kg Analysis 1. The type designation shows that the vehicle belongs to duty class M. 2. A box body with rigid sides is a torsionally rigid bodywork. Duty class M and torsionally rigid bodywork type gives the following recommendation according to the table under the heading "Bodywork type": Subframe Attachment in the front section of the subframe Attachment in the rear section of the subframe Bodywork type U-profile, 110x80x6 Flexible upwards Semi-flexible Reinforcement 09:40-01 Issue 4 en-gb 12 (17)

13 Example of subframe dimensioning 3. The vehicle must be equipped with components according to the requirements in the introduction. Information about the effect of the components is provided under the heading "Components". The vehicle has 3 axles and torsionally rigid bodywork, so the drawbeam based recommendation is described under the heading Drawbeam fitted on 3 or 4 axle vehicles with torsionally rigid or very torsionally rigid bodywork. The distance between the drive axle and connecting point is greater than the limit value of 2,400 mm and results in the following recommendation regarding reinforcement: Drawbeam Subframe Attachment in the front section of the subframe Attachment in the rear section of the subframe Reinforcement Single X-rod in chassis frame The drawbeam should be fitted in the fully underslung position. This results in the recommendation for the following reinforcement according to the heading Fully or semi underslung drawbeam: Drawbeam, underslung Subframe Attachment in the front section of the subframe Attachment in the rear section of the subframe Reinforcement End beam 09:40-01 Issue 4 en-gb 13 (17)

14 Example of subframe dimensioning The vehicle should also be equipped with a tail lift with a lifting capacity exceeding 2,000 kg. This results in the recommendation for the following rear attachment in the subframe and reinforcement according to the section Tail lift: Subframe Attachment in the front section of the subframe Attachment in the rear section of the subframe Reinforcement Tail lift Rigid Double X-rods in subframe 09:40-01 Issue 4 en-gb 14 (17)

15 Example of subframe dimensioning 4. Review each category individually. Subframe: Only the recommendation U profile, 110x80x6 is identified and is therefore the only one applicable. Attachment in the front section of the subframe: Only the recommendation flexible upwards is identified and is therefore the only one applicable. Attachment in the rear section of the subframe: The recommendations semi flexible or rigid are identified. Rigid attachment is selected here to handle the transfer of forces from the tail lift via the chassis frame to the subframe where the reinforcement is introduced. Reinforcement: Here the recommendations single X-rod in chassis frame, end beam and double X-rods in chassis frame are identified. The reinforcements end beam and double X-rods in the subframe are selected here, since these can be combined to obtain torsional rigidity in the rear overhang. Results: Subframe Attachment in the front section of the subframe Attachment in the rear section of the subframe Reinforcement Bodywork type U-profile, 110x80x6 Flexible upwards Semi-flexible Drawbeam Single X-rod in chassis frame Drawbeam, underslung End beam Tail lift Rigid Double X-rods in subframe Subframe Attachment in the front section of the subframe Attachment in the rear section of the subframe Reinforcement U-profile, 110x80x6 Flexible upwards Rigid End beam and double X-rods in subframe 09:40-01 Issue 4 en-gb 15 (17)

16 Frame dimensions Frame dimensions Subframe U-profile, 110x80x6. Subframe with side members in a U-profile with dimensions 110x80x6 mm (height x width x thickness) and I x =290cm 4. Crossmembers made in a U-profile with the same dimensions. U-profile, 140x80x6. Subframe with side members in a U-profile with dimensions 140x80x6 mm (height x width x thickness) and I x =500cm 4. Crossmembers made in a U-profile with the same dimensions. 09:40-01 Issue 4 en-gb 16 (17)

17 Interacting subframe Interacting subframe An interacting subframe can be considered on vehicles which are normally equipped with a double frame of the type F958 and where a low chassis weight is very important. By using a combined subframe in conjunction with an F950 chassis frame, the service weight can be reduced compared with the F958. Alternatively, a lower subframe can be used which provides a lower build height. Interacting subframes allow less movement between the chassis frame and subframe which can cause: Increased risk of frame oscillations Increased load on subframe and bodywork Concrete mixer truck Further information about chassis frame types is available in the document Chassis frames under Frames and subframes. Further information about the advantages of interacting subframes is provided in the document Interacting subframe under Calculations and theory. 09:40-01 Issue 4 en-gb 17 (17)