Hydrovacs.

Hydrovac trucks include a water tank, water wand connected to the water tank and water pump connected to pump water from the water tank to the water wand, mud tank, vacuum hose with dig tube connected to the mud tank, and blower to blow air from the mud tank and cause a negative pressure that draws material from the vacuum hose, as well as associated controls and drives. Water jets from the water wand are used to dig in soils, which creates a slurry, and the blower causes a vacuum in the mud tank that enables the dig tube to draw the slurry into the mud tank. Regulations limit weight on wheels of hydrovac trucks.

In addition, vibration from a hydrovac engine can cause maintenance issues for driving a hydrovac blower using a gear train.

The inventor noticed that typical rearward sloping floor designs make the weight of water and mud move to the rear of the hydrovac, putting potentially excessive load on the rear wheels. The proposed design has water is at the bottom and is a legal load going to the job. As the water gets used, the mud and water go to the second floor (mud tank) which loads more to the front to distribute the weight load onto all the wheels in the back and the front to allow maximum capacity.

A hydrovac with a belt drive for a hydrovac blower is also disclosed. The belt drive is provided with an air tensioning system. An articulated hydrovac is also disclosed.

These and other aspects of the device and method are set out in the claims.

Immaterial modifications may be made to the embodiments described here without departing from what is covered by the claims. In the claims, the word “comprising” is used in its inclusive sense and does not exclude other elements being present. The indefinite articles “a” and “an” before a claim feature do not exclude more than one of the feature being present. Each one of the individual features described here may be used in one or more embodiments and is not, by virtue only of being described here, to be construed as essential to all embodiments as defined by the claims.

A “hydrovac unit” as used herein comprises the necessary conventional components, some of which are for example described herein, to make a hydrovac unit work. When the word “mounted” is used, the item may be mounted directly or indirectly on the object referred to.

Referring to FIG. 1 and FIG. 2, there is shown a hydrovac in operational position (FIG. 1) and dumping position (FIG. 2). A conventional hydrovac unit 110 has a chassis 112 mounted on wheels 118, on the front of which is mounted a cab 114 and a conventional internal combustion engine 116. The cab defines the front of the hydrovac 110, the opposite end of the hydrovac being the rear. On the rear of the chassis 112 is mounted a mud tank 122, water tank 124 and mechanical components 126 for the mud tank 122 and water tank 124. In combination, the mud tank 122 and water tank 124 form a mud tank and water tank assembly 140. The mechanical components 126 include such conventional components as a blower, air filter, vacuum breaker, water pump and silencer, all of which are known in the art and used in conventional hydrovac units. A boom 128 is mounted on the mud tank 122. The boom 128 carries the conventional hose (not shown) that is used to dig holes for placing utility equipment such as utility poles. Controls (not shown) for the mud tank 122, hose and boom 128 may be mounted on a panel at the rear of the chassis 112, or the boom controls may be located on the wand.

The mud tank 122 has a hatch 131 (better seen in FIG. 3 and FIG. 4) and hydraulically operated cover 132 at the rear of the unit to allow dumping when the mud tank and water tank assembly 140 is raised to the dumping position shown in FIG. 2. Depending on the design of the mud tank 122, the dumping position will result from passage of the mud tank and water tank assembly 140 through a rotation angle of a set number of degrees, called here the dump angle. The assembly 140 may be lifted by a hydraulic lifting assembly 142 of conventional construction.

The water tank 124 is located under the mud tank 122, which in itself is conventional. However, in this case, the mud tank 122 deepens towards the front. The mud tank 122 may have a floor 134 that is flat, in which case the angle of the floor is downward toward the front of the unit. If the mud tank 122 has a floor 134 that is curved, then the average gradient is downward toward the front. The floor 134 should always have a slope in degrees that is lower than the dump angle, and be oriented oppositely. That is, while the floor 134 when viewed from the right side of the vehicle (looking forward) will be tilted down relative to horizontal in an acute angle in the clockwise direction, the dump angle will be a value measured counterclockwise. With the floor 134 having a slope less than the dump angle, in the dump position mud 136 in the mud tank 122 may exit the hatch 131 under force of gravity. To ensure efficient dumping, the dump angle should be larger than the floor slope by at least 10, 20, 30, 40 or 50 degrees. Exemplary angles are shown in the drawings.

With the mud weight going forward in the hydrovac, weight is distributed to the front of the vehicle 110 away from the wheels 118, enabling greater legal carrying capacity. The slope of the floor 134 means that, with a reasonable amount of water in the water tank 124, the hatch 131 is raised upward relative to existing hydrovacs. With a sufficiently high hatch, mud can be dumped directly into containers to be hauled away. With an air pocket needed above the mud in the mud tank 124, and considering that the unit should be too high, there is a limit to how high the hatch 131 can be placed. The floor 134 may slope downward from the hatch, and the floor steepness will determine the amount of water in the water tank 122. The slope of the floor 134 is therefore a balance between amount of water to be carried and desired forward weight shift, subject to the constraint that there must be enough space for the mud hatch within the rear of the hydrovac. Exemplary values for the tank capacities are shown in the figures.

The drive components (water or hydraulic pump, blower) of the hydrovac receive power from the engine of the hydrovac, typically a diesel engine. Power is supplied from the transmission of the engine via a shaft 150, which may be a split shaft with forward and rearward sections. A 

Wiki

• Hydrovac Tips and Tricks
• History of Hydrovac Excavation
• Hydrovac Patents

Dictionary

• Dictionary

Helpful Resources

• Hydrovac industry News