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  • Writer's pictureLiling Liu

[Chaos Physics] Unreal Engine 5.2 物理約束可掛接拖車車輛教學 |Physics Constraint Hitchable Trailer

Physics Constraint Hitch-able Trailer

Here to use Driving Chaos Vehicle Projects to make hitchable trailer


Import Mesh and Texture: Crab the model and texture into Browser

Trailer already rig and skin


FBX import Options:

Skeletal Mesh: turn on


Combine Meshes: If you have many separate mesh, you could turn on






Create BP:


Right click mouse > Blueprint Class


All Classes:

search: vehicle

Select “ WheeledVehiclePawn ”

Mesh >  Skeletal Mesh Asset > trailer

Wheel Setup


Select  Vehicle Movement Component


This trailer has two wheels so Press 2 times to add


Wheel Setup > Wheel Setups > +

Go to Skeleton and copy bone name


Select the bone > right click > Copy selected Bone Names




 Paste to Wheel setups index bone name

Turn on Simulate Physics

Trailer Physic


Open physics Asset

Select physic and delete


Because the default physic shape is not fit for the trailer

Select wheel bones > Primitive shape: Sphere >Add bodies

Select Root bone > Primitive shape: Single convex Hull >Add bodies

Input Action


Project settings

Go to Engine - Input

Action Mappings: Interact--> T



Obtain the behaviors we want for our vehicle.


Select trailer skeleton > right click mouse > Create > Anim Blueprint

Opne AnimBP > Class Settings > class options > Parent Class : Vehicle Animation Instance



Mesh Space Ref Pose: this is used to return the mesh space reference pose for our skeletal mesh in the Animation Blueprint


Wheel Controller : offloading a lot of the work in creating these types of animations, you can use the Wheel Controller Node to drive the animations.

GO to BP_trailer


Select Mesh > Animation > Anim Class : ABP_trailer

Prepare Interaction Object




Add Collision, and naming: Docking.

Blueprint > Blueprint Interface


A Blueprint Interface is a collection of one or more functions - name only, no implementation - that can be added to other Blueprints. This is essentially like the concept of an interface in general programming, which allows multiple different types of Objects to all share and be accessed through a common interface.

Functions: Interact

Inputs: car (BP_Car, object reference)

Open BP_car


Use for loop to check does implement interface, if true, does interact

Opne BP_Trailer


Add Collision


Naming: Trigger_coli

Add PhysicsConstraint


A physics constraint is a joint that allows you to connect two Actors or component together and also apply limits or forces on them.


Conponent name 1: Mesh

Conponent name 2: Trigger_coli


Control Physics constraint - Angular Limits


Swing 1 motion  (Z) : Limited, swing 1 limted: 60

Swing 2 motion (x): Locked

Twist motion (y): Locked

Add Text Render

1. Text: type the information.

2.Turn off visibility

Add cube


In order to let trailer to stand on the ground, so add cube

Add Interface


Class Settings > Implemented Interfaces > select BI_Interact

Add variables:

1. CanHitch :Boolean

2. TryHitch : Boolean


Select trigger_collision box add begin overlap and end overlap


When End overlap,  try Hitch: turn off, and text does not show

When begin overlap,  try Hitch: turn on


Get  car docking and trailer trigger_coli’s world location and do float to integrate value

Does car docking X subtract trailer trigger X to get the value. The value is less equal what we want the value. However, we might be get the negative value, so here I use ABS to get positive value.


Does car docking Y subtract trailer trigger Y to get the value. The value is less equal what we want the value.


X and Y value both are true and return true.

Set true/false to can Hitch

Set text visibility and delay the time.

After completed, try hitch again to condition, if true, cast to bp_Car

Interact Event


If can hitch, the car connect to trailer to get movement and set constraint components. Turn off try hitch and set text visibility.

Otherwise, when press T again, release the throttle and break constraint, and  set try hitch: turn on




When the car connects into the trailer, the stand is disappear.



Creat function: RemoveStand

Add Variables: StandRemovedBool :bool

Open RemoveStand function:

Destory stand compoent, and set standRemovedBool: on, and call stand removed

Event Dispatchers: StandRemoved

Event graph


Using event tick to do event StandRemoved.

If stand is valid, remove stand. If not, do once to print string

Event Interact:

Remove stand event and turn off standRemovedbool



Youtube Tutorial:

Plugins: ChaosVehiclesPlugin



Sketchfab  -  Car Scene:


Sketchfab  - Generator Trailer:



Physics Constraint Component:




How to Set up Vehicles Unreal Engine 5.0


Ref: Unreal Engine Truck Tutorial: Trailer System

教學專案和文件下載 /  Full Project and Document Download:




贊助 / Support Me




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