Machine Elements · Course project

Design of Automotive Towing Devices

A step-by-step design algorithm for a class F towing device: from the design brief and the static model, through the sizing of every element and joint, to numerical checks in MDESIGN and ANSYS and the full set of AutoCAD drawings.

Start with section 1.1.1 See all ten stages

General structure of a class F automotive towing device mounted at the rear of a car — General structure of a class F towing device

Authors	Gh.L. Mogan, I.D. Buzdugan
Institution	Transilvania University of Brașov
Product	Automotive Towing Device (ATD), UNECE R55 class F	Tools	MDESIGN · ANSYS · AutoCAD

The device, subassembly by subassembly

The design follows the load path from the tow ball to the vehicle body. Each subassembly gets its own chapter.

S1Towing hook and upper tie rodElements 1, 4, 5 · threaded joint 1-4, welded joint 4-5
S2Upper column, body and lower tie rodElements 5–8 · tube-in-tube or pin joint 5-6, welded joint 6-7
S3Lower tie rod to cross beamJoints 7-8 and 8-9
S4Cross beamElements 9–12′ · bolted, welded, tube-in-tube and pin joints
S5Side tie rodsElements 13, 13′ · welded joints 12-13

Sec theory and design procedure Ex worked example with numbers Guide software guide (MDESIGN, ANSYS, AutoCAD) Annex reference tables and standards

Design algorithm

General aspects and design brief

The towing device as a product, the objectives of the project and the data that define your variant.

1.1 Description and construction of ATD products
1.1.1Description of ATD productsSec.1.1.1
1.1.2Construction of class F ATDsSec.1.1.2
1.2 Project objectives and design data
1.2.1Project objectivesSec.1.2.1
1.2.2Design dataSec.1.2.2 Ex.1.2.2

Structural-constructive scheme and static analysis

From the real device to a bar-structure model, then the loads acting on every element and joint.

2.1Structural-constructive schemeSec.2.1
2.2Static analysisSec.2.2

Design of element 1 (towing hook) and subassembly S1

Towing hook, upper tie rod, upper column and the threaded and welded joints between them.

3.1Design of element 1 (towing hook)Sec.3.1 Ex.3.1
3.2Design of element 4 (upper tie rod)Sec.3.2 Ex.3.2
3.3Design of joint 1-4 (threaded joint)Sec.3.3 Ex.3.3
3.4Design of element 5 (upper column)Sec.3.4 Ex.3.4
3.5Design of joint 4-5 (welded joint)Sec.3.5 Ex.3.5
3.6Checking element 4 (upper tie rod) with MDESIGNGuide.3.6 Ex.3.6
3.7Checking joint 4-5 (welded joint) with MDESIGNGuide.3.7 Ex.3.7
3.8Representation in the assembly drawing, stage 3Guide.ACAD.01 Ex.ACAD.3.8

Design of subassembly S2

The connection between the upper column and the body, the lower tie rod, and their checks in MDESIGN and ANSYS.

4.1Design of joint 5-6 (tube-in-tube joint)Sec.4.1 Ex.4.1
4.2Design of joint 5-6 (pin joint)Sec.4.2 Ex.4.2
4.3Design of elements 7, 8 (lower tie rod, body)Sec.4.3 Ex.4.3
4.4Design of joint 6-7 (welded joint)Sec.4.4 Ex.4.4
4.5Checking elements 5, 6 (upper column, body) with MDESIGNGuide.4.5 Ex.4.5
4.6Checking joint 5-6 (tube-in-tube joint) with ANSYSGuide.4.6 Ex.4.6
4.7Checking joint 5-6 (pin joint) with MDESIGNGuide.4.7 Ex.4.7
4.8Checking joint 6-7 (welded joint) with MDESIGNGuide.4.8 Ex.4.8
4.9Representation in the assembly drawing, stage 4Guide.ACAD.01 Ex.ACAD.4.9

Design of subassembly S3

Joints 7-8 and 8-9: tube-in-tube, pin and welded connections, verified numerically.

5.1Design of joint 7-8 (tube-in-tube joint)Sec.5.1 Ex.5.1
5.2Design of joint 7-8 (pin joint)Sec.5.2 Ex.5.2
5.3Design of joint 8-9 (welded joint)Sec.5.3 Ex.5.3
5.4Checking elements 7, 8 (lower tie rod, body) with MDESIGNGuide.5.4 Ex.5.4
5.5Checking joint 7-8 (tube-in-tube joint) with ANSYSGuide.5.5 Ex.5.5
5.6Checking joint 7-8 (pin joint) with MDESIGNGuide.5.6 Ex.5.6
5.7Checking joint 8-9 (welded joint) with MDESIGNGuide.5.7 Ex.5.7
5.8Representation in the assembly drawing, stage 5Guide.ACAD.01 Ex.ACAD.5.8

Design of subassembly S4

The cross beam: central and side bars, their tube-in-tube, bolted, welded and pin joints.

6.1Design of elements 11, 12, 12′ (central bar, left/right bar)Sec.6.1 Ex.6.1
6.2Design of joints 11-12, 11-12′ (tube-in-tube joints)Sec.6.2 Ex.6.2
6.3Checking elements 11, 12/12′ (central, left/right bar) with MDESIGNGuide.6.3 Ex.6.3
6.4Design of joint 9-10 (bolted joints)Sec.6.4 Ex.6.4
6.5Checking joints 11-12, 11-12′ (tube-in-tube joints) with ANSYSGuide.6.5 Ex.6.5
6.6Design of joint 10-11 (welded joint)Sec.6.6 Ex.6.6
6.7Design of joints 11-12, 11-12′ (pin joints)Sec.6.7 Ex.6.7
6.8Checking joints 11-12, 11-12′ (pin joints) with MDESIGNGuide.6.8 Ex.6.8
6.9Representation in the assembly drawing, stage 6Guide.ACAD.01 Ex.ACAD.6.7

Design of subassembly S5

Left and right tie rods and their welded joints to the side bars.

7.1Design of elements 13 and 13′ (left/right tie rod)Sec.7.1 Ex.7.1
7.2Design of joints 12-13 and 12′-13′ (welded joints)Sec.7.2 Ex.7.2
7.3Checking joints 12-13 and 12′-13′ (welded joints) with MDESIGNGuide.7.3 Ex.7.3
7.4Representation in the assembly drawing, stage 7Guide.ACAD.01 Ex.ACAD.7.4

Design of element 2 and of joints I, E

Vehicle brackets, the bolted output joint to the car body, the ball-joint input and the coupling spring.

8.1Design of elements 2 and 2′ (left/right bracket)Sec.8.1 Ex.8.1
8.2Design of joints 13-2 and 13′-2′ (bolted joints)Sec.8.2 Ex.8.2
8.3Checking elements 13, 2 with ANSYSGuide.8.3 Ex.8.3
8.4Design of the output joint E (bolted joints)Sec.8.4 Ex.8.4
8.5Checking the input (towing) joint I (ball joint)Sec.8.5 Ex.8.5
8.6Design of the helical spring of the towing couplingSec.8.6 Ex.8.6
8.7Representation in the assembly drawing, stage 8, and its completionGuide.ACAD.01 Ex.ACAD.8.7

Working drawings

Detail drawings ready for manufacturing, with the conventions they require.

9.0Working drawings — reference materialAnnex.9.0
9.1Working drawing: towing hookGuide.ACAD.02 Ex.ACAD.9.1
9.2Working drawing: subassembly S4Ex.ACAD.9.2
9.3Working drawing: cylindrical helical springEx.ACAD.9.3

Technical documentation

Writing up the technical report that accompanies the drawings.

10.1Preparing and writing the technical reportSec.10.1 (PDF, Romanian)Ex.10.1 (DOCX, Romanian)

Reference material

Annexes are opened from the sections where they are needed; they are collected here for quick lookup. PDF annexes and examples are kept in their original Romanian form.