Unity3D Part Movement - unity3d

Question

With the help from people here (and the Unity forum) I am almost happy with the build i am making.
This build is showing a Booster Pump, used for boosting waterpressure for industrial cleaning.
So far i can zoom, rotate, Pan and press keys 1-3 to show/hide internal parts.
I would like to make the internal parts MOVE out to position on keypress, instead of just appearing in position (like they do now - 1st. image), so I have this movement script.
But when i rotate/move the Booster Pump, the it does not look right (2nd image).
The moved part is not following the main part of the Booster Pump.
From what I gather it have to do with local or world space, but I dont know which and how to implement it?
enter image description here
enter image description here
{
Vector3 EndPos;
Vector3 StartPos;
private float distPos;
public float MovSpeed;
private float direction = 0f; // The direction of travel
public float maxDistance = 2f; // The maximum move distance
void Start()
{
StartPos = transform.position;
EndPos = StartPos + Vector3.back * maxDistance;
}
void Update()
{
if (Input.GetKey(KeyCode.Space) && distPos == 1f)
direction = -1f;
if (Input.GetKey(KeyCode.Space) && distPos == 0f)
direction = 1f;
distPos = Mathf.Clamp01(distPos + (Time.deltaTime * MovSpeed * direction));
if (distPos == 0f || distPos == 1f) direction = 0f;
transform.position = Vector3.Lerp(StartPos, EndPos, distPos);
}

Answer 1

If the internal parts are child objects of the parent, and you want them to move around independently while also continuing to rotate and move with their parent, you should change their localPositions. By changing local position instead of world, you are telling them to move that distance away from their initial positions, relative to the center of their parent - no matter where the parent is or how it's rotated at the time.
Try changing
StartPos = transform.position;
to
StartPos = transform.localPosition;
and then change
transform.position = Vector3.Lerp(StartPos, EndPos, distPos);
to
transform.localPosition = Vector3.Lerp(StartPos, EndPos, distPos);