Rather than us explain all the rules.....
You read them than tell us what you do not understand.
§ 393.128What are the rules for securing automobiles, light trucks and vans?(a) Applicability. The rules in this section apply to the transportation of automobiles, light trucks, and vans which individually weigh 4,536 kg. (10,000 lb) or less. Vehicles which individually are heavier than 4,536 kg (10,000 lb) must be secured in accordance with the provisions of §393.130 of this part. (b) Securement of automobiles, light trucks, and vans.
(1) Automobiles, light trucks, and vans must be restrained at both the front and rear to prevent lateral, forward, rearward, and vertical movement using a minimum of two tiedowns.
(2) Tiedowns that are designed to be affixed to the structure of the automobile, light truck, or van must use the mounting points on those vehicles that have been specifically designed for that purpose.
(3) Tiedowns that are designed to fit over or around the wheels of an automobile, light truck, or van must provide restraint in the lateral, longitudinal and vertical directions.(4) Edge protectors are not required for synthetic webbing at points where the webbing comes in contact with the tires.
§ 393.130What are the rules for securing heavy vehicles, equipment and machinery?
(a) Applicability. The rules in this section apply to the transportation of heavy vehicles, equipment and machinery which operate on wheels or tracks, such as front end loaders, bulldozers, tractors, and power shovels and which individually weigh 4,536 kg (10,000 lb.) or more. Vehicles, equipment and machinery which is lighter than 4,536 kg (10,000 lb.) may also be secured in accordance with the provisions of this section, with §393.128, or in accordance with the provisions of §§393.100 through 393.114.
(b) Preparation of equipment being transported.
(1) Accessory equipment, such as hydraulic shovels, must be completely lowered and secured to the vehicle.
(2) Articulated vehicles shall be restrained in a manner that prevents articulation while in transit.
(c) Securement of heavy vehicles, equipment or machinery with crawler tracks or wheels.
(1) In addition to the requirements of paragraph (b) of this section, heavy equipment or machinery with crawler tracks or wheels must be restrained against movement in the lateral, forward, rearward, and vertical direction using a minimum of four tiedowns.
(2) Each of the tiedowns must be affixed as close as practicable to the front and rear of the vehicle, or mounting points on the vehicle that have been specifically designed for that purpose.
§393.130 What are the rules for securing heavy vehicles, equipment and machinery?
Question 1: If an item of construction equipment which weighs less than 4,536 kg (10,000 lb.) is transported on a flatbed or drop-deck trailer, must the accessory equipment be lowered to the deck of the trailer?
Guidance: No. However, the accessory equipment must be properly secured using locking pins or similar devices in order to prevent either the accessory equipment or the item of construction equipment itself from shifting during transport.
Question 2: How should I secure the accessories for an item of construction equipment which weighs 4,536 kg (10,000 lb.) or more, if the accessory devices would extend beyond the width of the trailer if they are lowered to the deck for transport?
Guidance: The accessory devices (plows, trencher bars, and the like) may be transported in a raised position, provided they are designed to be transported in that manner. However, the accessory equipment must be locked in place for transport to ensure that neither the accessories nor the equipment itself shifts during transport.
Question 3: A tractor loader-backhoe weighing over 10,000 pounds is being transported on a trailer. The loader and backhoe accessories are each equipped with locking devices or mechanisms that prevent them from moving up and down and from side-to-side while the construction equipment is being transported on the trailer. Must these accessories also be secured to the trailer with chains?
Guidance: No. However, if the construction equipment does not have a means of preventing the loader bucket, backhoe, or similar accessories from moving while it is being transported on the trailer, then a chain would be required to secure those accessories to the trailer.