A propping agent for fractures produced in the walls of a bored well comprising a granular or particulate product containing on the basis of its oxide content up to 85% by weight zirconium oxide (ZrO.sub.2) in a quantity which is such that the weight ratio of ZrO.sub.2 /SiO.sub.2 is equal to or greater than 1.5, alumina (Al.sub.2 O.sub.3) in a quantity which is such that the weight ratio Al.sub.2 O.sub.3 /SiO.sub.2 is between 0 and 1.5 and sodium oxide (Na.sub.2 O) in a quantity which is such th...

A retractable step for use with a vehicle comprises a stepping member having a stepping deck, a first arm, and a second arm. The first arm has a first end pivotally attached to the vehicle, and a second end pivotally attached to the stepping member. The second arm also has a first end pivotally attached to the vehicle, and a second end pivotally attached to the stepping member.

A retractable step for use with a vehicle comprises a stepping member having a stepping deck, a first arm, and a second arm. The first arm has a first end pivotally attached to the vehicle, and a second end pivotally attached to the stepping member. The second arm also has a first end pivotally attached to the vehicle, and a second end pivotally attached to the stepping member.

A powered running board assembly has a deck and at least two hinges extending from the deck for mounting longitudinally the deck to an underside of a vehicle. Each hinge has a mounting bracket configured to mount to the underside of the vehicle. A pair of links pivotally extending between the deck and mounting bracket. The deck is movable between a retracted position and an extended position. A linear drive assembly operably engages at least one of the hinges to drive the deck between the retrac...

A step apparatus includes a step body that can move between a projecting position where the step body projects from a side surface of the vehicle and a retracted position where the step body is retracted behind the side surface of the vehicle, a drive unit for driving the step body, the drive unit including a rope-shaped member connected to the step body, a rotating drum around which the rope-shaped member is wound, and a drive motor that rotates the rotating drum, and a guide unit for guiding t...

A deployable step and body-side assembly including a step body-side structure, one or more link assemblies, and an actuator. The step body-side structure is attached to the vehicle by the link assemblies. Each link assembly includes a carrier, an extending arm, a first link, a second link, a first rotating arm, and a second rotating arm. The carrier is attached to the step body-side structure and pivotally attached to the extending arm. The extending arm is pivotally attached to the vehicle by t...

A retractable step for use with a vehicle comprises a stepping member having a stepping deck, a first arm and a second arm. The first arm has a first end pivotally attached to the vehicle, and a second end pivotally attached to the stepping member. The second arm also has a first end pivotally attached to the vehicle, and a second end pivotally attached to the stepping member.

A retractable running board assembly is mounted to the frame of a vehicle. The running board is selectively extendable between a retracted position, which is close to the vehicle's frame, a lower, laterally-outward extended position that facilitates easy entrance into and exit from the vehicle and a roof-access position, higher and outward from the entrance position. A selectively-operable driving mechanism actuates a link to extend and retract the running board. When the driving mechanism is no...

A retractable step for use with a vehicle comprises a stepping member having a stepping deck, a first arm, a second arm, a motor and a stop. The first arm has a first end pivotally attached to the vehicle, and a second end pivotally attached to the stepping member. The second arm also has a first end pivotally attached to the vehicle, and a second end pivotally attached to the stepping member. The motor is drivingly connected to the first arm such that a rotation of the motor causes rotation of ...

A method of fracturing using deformable proppants minimizes proppant pack damage, without compromising the fracturing fluid's proppant transport properties during pumping, by use of deformable proppants. Selection of proppant is dependent upon the mechanical properties of the formation rock. The strength of the deformable proppant is dependent upon the modulus of the formation rock being treated such that the proppant is capable of providing, at the very least, a minimum level of conductivity in...