A trailer assembly suitable for carrying a container of proppant has a frame with a first side rail and a second side rail extending in generally parallel relation to each other and a plurality of wheels rotatably mounted below the frame. The frame has a plurality of cross members extending between the side rails. First and second outriggers extend across the side rails so as to each have one end extending outwardly of one of the side rails and an opposite end extending outwardly of the other side rail. The first and second outriggers are suitable for receiving the container of proppant thereon. The frame has a first section positioned above the wheels and a second section positioned at a level lower than a level of the first section. The proppant container is placed on the first section.

A mobile well service unit has: a structural frame such as a chassis with ground engaging members; and a telescoping platform assembly mounted at a rear end of the structural frame, the telescoping platform assembly having a lower platform mounted to slide up and down relative to the structural frame, and an upper platform mounted to the lower platform to slide up and down relative to the lower platform. A mobile well service unit has: a structural frame with ground engaging members; a platform mounted at a rear end of the structural frame to slide up and down relative to the structural frame; and a set of telescoping and self-levelling stairs with an upper end pivotally anchored to the platform, and a lower end pivotally anchored to the structural frame.

A rotatable trailer bed includes a frame, a trailer bed, a turntable swivel assembly, and a plurality of swivel casters. The frame includes a bed section, a hitch section, and two wheel sets. The hitch section is adjacently connected a front end of the bed section. The two wheel sets is rotatably mounted to the bed section. The plurality of swivel casters is mounted to the bed section is perimetrically positioned around the bed section. The trailer bed is rotatably mounted to the bed section through the turntable swivel assembly as the plurality of swivel casters maintain the balance and level of the trailer bed.

A trailer for carrying plate glass has an elongated deck and an elongated rigid beam that extends above the deck. The beam supports plate glass transported by the trailer. The deck and the beam may be made from aluminum.

A roll off trailer having a stepped out neck is provided. The trailer frame may be formed largely of an aluminum alloy or other metal.

A method for slowing transfer of a heavy work machine on a sloping base using a transportation device equipped with wheels, the work machine including a body, a crawler chassis fitted beneath the body, a set of booms having at least one operating cylinder, a first end and a second end, said set of booms being pivoted at the first end to the work machine and a selected auxiliary device is pivoted at the second end, and a brake surface connected to the auxiliary device, in which method includes the steps of transferring the work machine by supporting the work machine on the crawler chassis at least partly on top of the transportation device, towing the work machine using a transfer vehicle with the aid of the transportation device, using said operating cylinder of the set of booms to press the brake surface against the sloping base to create friction to slow transfer speed of the transportation device on the sloping base, and adjusting pressing of the brake surface taking place through the auxiliary device using the operating cylinder or one set of booms. An arrangement in connection with a heavy work machine for transferring the work machine on a sloping base is also described.

A trailer including a hydraulic steering system includes: a trailer body; a plurality of axles connected to the trailer body; a steering cylinder connected to at least one axle of the plurality of axles and configured to turn the at least one axle; a sensing cylinder; a controller; and a hydraulic steering system. The hydraulic steering system includes a hydraulic circuit including a plurality of hoses and valves, and the steering cylinder is in fluid communication with at least one of the sensing cylinder and the controller. The hydraulic steering system is configured to transition between: (1) an automatic steering mode and (2) a manual steering mode. A towing system and a method of steering a trailer are also disclosed.

A booster axle assembly includes a wheel axle, a suspension system coupled to the wheel axle, a booster frame supported by the suspension system, a main link coupled via a first hinged connection to a rear portion of the booster frame and extending from the first hinged connection in an upward and forward direction, a lock assembly coupled to a forward end of the main link via a second hinged connection, and a lockup frame (with a curved bottom portion that defines a cradle) coupled to a front end of the booster frame by a third hinged connection and coupled to the lock assembly by a fourth hinged connection and a fifth hinged connection.

A rotatable trailer bed includes a frame, a trailer bed, a turntable swivel assembly, and a plurality of swivel casters. The frame includes a bed section, a hitch section, and two wheel sets. The hitch section is adjacently connected a front end of the bed section. The two wheel sets is rotatably mounted to the bed section. The plurality of swivel casters is mounted to the bed section is perimetrically positioned around the bed section. The trailer bed is rotatably mounted to the bed section through the turntable swivel assembly as the plurality of swivel casters maintain the balance and level of the trailer bed.

A trailer neck reinforcement structure includes a first beam reinforcement structure including: (i) a first beam inner insert connected to an inner side of the first beam; and, (ii) and a first beam outer insert connected to an outer side of the first beam. A second beam reinforcement structure includes: (i) a second beam inner insert connected to an inner side of the second beam; and, (ii) and a second beam outer insert connected to an outer side of the second beam. Internal cross members extend between the first and second beam inner inserts. A first group of external cross members is located between the first beam outer insert and the left side rail, and a second group of external cross members is located between the second beam outer insert and the right side rail. Each external cross member comprises an inner segment connected to an outer segment.