Very low cost, high performance, self-propelled, highway legal, shotcrete pump
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The usefulness of an item or a process is largely a function of its cost. The perfect historical example of this is the cotton gin. This cheap machine so lowered the labor cost of removing the seeds from cotton fibers that cotton cloth became commonplace. This, among other things, helped fuel the industrial revolution. Likewise, the cost of building a home of concrete covered 3-d panels is out of the reach of most retired Americans in year 2002. The labor cost of applying concrete to these panels by trowels is prohibited. Also, the cost of using a Shotcrete system prices a 3-d panel home out of the reach of most retirees. This invention creates a Shotcrete pump for less than $2000. and can be built by any low skilled “weekend dabbler” using handtools. With this machine the house payment of a snug safe home costs $180 per month.

Littleton, Earl Raymond (Pearland, TX, US)
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F04B43/12; (IPC1-7): F04B43/12
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1. What I claim as my invention is a very low cost highway legal shotcrete pump



[0001] A used, low cost highway vehicle can be converted into a self-propelled Shotcrete pump in a series of low cost and low skill steps. The vehicle can be a four-door car or a half-ton pickup truck. The car would cost $400 to $600 and the truck $800 to $1000. The prices are for Houston, Tex. in year 2002, but are comparable throughout the U.S. The truck is easier to work with, but not much.

[0002] It is better to have the vehicle licensed, safety inspected, and otherwise made highway legal before conversion. Nothing in the conversion will make the vehicle unsafe, and I have had a Shotcrete Pump inspected after conversion. However, the sight of a converted Shotcrete Pump pulling into their driveway can be quite discombobulating to the uninitiated employees of a safety inspection station.

[0003] The vehicle conversion summarized, detailed and illustrated here is a four-door car. However, only the first step is different if a pickup truck is used.

[0004] Step 1 When using a pickup truck, just remove the truck bed. When using a four-door car, starting at the side post between the back and front doors of the car, cut the back half of the car's body away. Starting behind the side post, cut across the roof of the car. At 90 degrees down from this roof cut, saw across the floorboard. Avoid the frame of the car, any wires, and any pipes such as brake lines and fuel lines. The back opening of the car will be closed later with lumber. It is this car bodywork that is avoided by use of a pickup truck. All cutting only needs a handheld jig saw. Mark the wires with tape as to what goes to the brake lights and backup lights, etc. Cut the marked wires loose from the lights. Discard the rear doors and the back of the body.

[0005] Step 2 Remove the shock absorbers and springs from the frame and rear axel. The frame is now setting on the “bump pad” of the rear axel. Attach a heavy chain to the frame in front of the axel using ⅜-inch grade 8 bolts. Attach the same type chain in the same way to the frame behind the axel. Firmly tighten the chains around the axel with grade 8 bolts connecting the last links of the two chains. Use washers and locking nuts. Do this to both sides of the vehicle. It is absolutely required that the frame and axel be locked together. This makes for a bumpy ride down the highway, but when concrete is poured into the pumping hopper, the frame does not move in relation to the axel.

[0006] Step 3 The pump will be placed on the left rear wheel so as to be near the vehicle controls. To lock the right rear wheel, take a lug nut off the right rear rim. The lug removed should be the one closest to the back of the vehicle. Place a heavy chain over the lug bolt and replace and tighten the lug nut. Cut the chain so that it can be attached to the frame with a ⅜-inch grade 8 bolt. The chain should have just enough play so that it can easily be placed on and removed from the lug bolt. It can be seen that once the lug chain is in place, the right wheel cannot turn and all the engine power will go to the left wheel. When the pump is driven on the highway between building sites, the lug chain will be removed from the lug bolt and wired to the frame so it does not drag on the road.

[0007] Step 4 Obtain a rim the same size as the other rims on the converted pump. Weld to this rim three ⅝-inch grade 8 bolts, 12.5 inches long. The outer edge of the rim will be cut and bent down so that a gap ⅝ inch wide is created that can receive the shank of the bolt. This is to be done in three places equidistance around the outer edge of the rim. The three bolts will be welded across the rim with the heads jammed against the inside of the inner edge and the shanks fitted into the ⅝-inch gaps in the outer edge. This leaves three firmly attached threaded bolts protruding 6 inches outside of the outer rim edge pointing away the vehicle. These three bolts will act as the shaft for the impellers. See photo. (Photo #0017)

[0008] Step 5 The three above-described bolts will hold the three pneumatic tires, which act as the pump impellers. Each of these tires is a 4″×12″ tube type mounted on a 5″ rim. This type of rim is constructed with four ⅜-inch bolts of standard “High Grade” type. These four bolts must be removed and replaced with the same size bolts of grade 8 types.

[0009] Step 6 Each of the impeller shafts will have enough ⅝ washers placed on the inner side of the impeller to keep the rubber of the impeller tire away from the outer rim edge, even when the sides of the impeller tires bulge during the compression of pumping. The ⅝-inch bolts are inserted through the bearing shaft openings. A washer is placed on each of the bolts, and a ⅝-inch nut is placed with a “jammer”, i.e., with a jam nut. These two nuts hold the impeller in place, but allow it to spin freely during pumping. It can be seen that the outer surface of the impellers will subscribe a circle 25 inches in diameter when the rim is turning.

[0010] Step 7 The body of the pump can be made of medal or of timber. Timber tools are more universally available and less skill is needed, so timber is used in this description. If anti-decay treated lumber is used, the cost is higher and the weight is greater, but the pump will last for many years. It can even be transferred onto another vehicle when the current one wears out.

[0011] The pump body is a wooden block 60 inches long by 24.5 inches high, and 5.25 inches thick; with a 18.5″ deep and 26.5″ wide open notch, so cut as to receive the impeller tires spinning against the inside of the notch.

[0012] The pump body can be made from 2×10s, 2×6s, and 1×6s. The preceding lumber pieces are written by name, not by dimension. American lumber is named somewhat larger in width and height than the true dimension. A 2×10 measures 1.5″ by 9.5″, and a 1″ by 6″ measures 0.75″ by 5.5″. To achieve the 60 inches long by 24.5 inches high, by 5.25-inch thickness of the pump body, one needs six 2″×10″×60″, three 2″×6″×60″ and eleven 1″×6″×24.5″

[0013] Place two 2″×10″ on the bottom of the 24.5 inches pump body and one 2″×6″ on the top to form a surface 60″ long by 24.5″ wide by 1.5″ thick. Over one 24.5″ edge, nail two pieces 0.75″ by 5.5″ by 24.5 inches long. Use enough nails to hold the five boards firmly. Draw the saw line for the 26.5-inch wide by 18.5-inch deep notch at this time so that nails can be placed to avoid the saw line. To draw the saw line, find the center of the top 60-inch board by measuring and marking 30 inches from one end. Measure and mark a point five inches down from this mark on the edge. Drive a small nail ½ inch deep into the wood at this spot. Tie a string to the nail and at 13.25 inches loop the string around a pencil point and back to the nail, wrapping and tying. The point of the pencil should be 13.25 inches from the nail. The circumference of the partial circle marked by this string is the saw line for the 26.5″ by 18.5″ notch. Place and nail the next two 24.5 inch lumber pieces, staring at the other end of the 60-inch block. Place and nail 6 of the remaining seven 24.5 pieces, 3 on each end. Mark the saw line with each piece and avoid the saw line with each nail. The last centerpiece will be inch too wide to fit. Measure and rip (cut long ways) this last piece. Before removing the nail draw the diameter of the circle, parallel with the top edge. Remove the nail, and fit and attach the piece. With a flexible piece of cardboard, draw the saw line on the last board.

[0014] At the point where the diameter line crosses the partial circle on the right hand side, draw a perpendicular line up to the top edge. Do likewise on the left hand side: draw a line perpendicular to the top edge from the diameter-line-partial-circle-line crossing point. It can be seen that the saw line now consists of two parallel lines, each 13.5 inches from the center of the top edge, and running down 5 inches from the top, terminating at the diameter of a semicircle 26.5″ wide. With the jigsaw, using the thinnest, narrowest possible blade, cut along the drawn saw line.

[0015] The vehicle pumps by compressing a high grade, 2-inch diameter hose between the impellors and the surface of the notch in the pump body. The way it currently exists, the pump body has sharp 90-degree edges at the top of the pump notch. To prevent these edges from cutting into the hose, we must round off the notch edges with 2 inch quarter round cuts. Measure down both sides from the top edge into the notch and mark a point 2 inches saw from the top edge. Do the same along the top edge; mark a point on the top edges on both sides of the notch of the top edge 2 inches from the notch edge toward the ends of the pump body. Draw a straight line connecting these points, forming two triangles with 2-inch sides and a 2.83-inch hypotenuse. Determine the mid point of the hypotenuse on both sides by a piece of paper, cutting the paper to exactly the same width as the hypotenuse, and folding the paper in half. Use this folded paper to find the center point of the hypotenuse on both sides. Drive a small nail into this point. Using a loop in a piece of string, draw a semicircle rounding out the edge. Draw this saw line on both sides of the pump body. With the jigsaw, using the thinnest, narrowest possible blade, cut along the drawn saw line.

[0016] Place and nail the next three boards, two 2×10s and one 2×6. Place the boards so that the cracks between the under laying timbers do not match the current layer, giving the structure as much strength as possible.

[0017] Using the jigsaw cut the new boards. The new boards do not have a saw line, however, the edge of the existing notch can be used as a saw guide. Turn the pump body up on its bottom edge with the notch on top. Using the notch-new board junction as a guide cut away the new layer from the notch. Place and nail the last lumber layer and cut the notch again.

[0018] Two 1 inch by 6-inch planks must now be placed across the bottom of the notch; one on each side. This is to prevent the plumping hose from being forced out of the notch during the pumping process. These planks must have a rounded side edge on the topside to prevent damage to the pumping hose. These shelve planks can easily be ordered and/or purchased from a lumber store. They will measure 1″×6″×34″ and will have a rounded side edge. They will be attached across the center-bottom edge of the notch, with the bottom edge of each plank 1″ below the bottom edge of the notch. Again, these planks will be attached to the back of the pump body (toward the vehicle) and the front of the pump (away from the vehicle). The rounded edge will point upward. These planks must be placed so that the axils of the impellor wheels will miss them. The back plank can be nailed into place. However, the front plank must be attached on each side with a single lag bolt with washer. It will need to be removed and replaced when the pump hose is attached and again when it is detached. (See photo 0009) The end of the pump hose closest to the hopper is attached to the bottom of the hopper and so is held firmly in place. Likewise the end furthest from the hopper must be firmly attached. Any 2″ piece of iron pipe will function. The iron pipe will be chained to the pump body. It will have a female hose attachment on one end to connect the pumping hose and a male hose attachment on the other end to attach the Shotcrete gun hose This completes the building of the pump body. (See photo 0003)

[0019] Dimension lumber has been used to describe the above building of the pump body. This allows very cheap lumber to be used, even scrap or salvaged lumber. However, at reasonable expensive less skill would be needed to,

[0020] A. Hire a carpenter to build the body

[0021] B. Use seven ¾ plywood sheets, cut into 24.5 inch by 60 inch pieces.

[0022] C. Both a carpenter and the use of plywood

[0023] Step 8 Obtain about 8 feet of 3 inch by 3 inch by {fraction (3/16)}-inch angle iron. Cut two lengths 22 inches long. These will be bolted to the vehicle side of the pump body. Drill four holes in each of the angle irons that will allow passage of 6-inch long ⅜-inch bolts. Put the vehicle onto a level concrete surface so it can be jacked up without the jacks pressing into the ground. Jack up both sides of the back of the vehicle, bracing the front wheels so the vehicle will not roll off the jacks. Bolt the impellor rim on the left wheel with the lug nuts. Place the vehicle in neutral gear so the left wheel can spin freely. Place the pump body under the impellors and bolt the three-impellor wheels into place, using washers as necessary to separate the impellor wheel rubber from the rim edge. Lower both sides of the back of the vehicle so that it stays level and the impellor wheels touch the bottom of the sawed out notch. The vehicle is now at the level it will be at while pumping concrete. Measure the height of the frame from the ground and make two jack stands from the lumber cut from the pump body notch. Made sure the bottoms of the stands are each resting on a piece of 2×10 so the stands will not sink into the ground. Mark the frame so the stands can be correctly placed under both sides of the frame to quickly obtain the correct height when assembling the pump. When using the pump as well as when working on it, it is best to brace both front wheels, jack up the back until the stands can be placed, lower the frame until the jacks are holding the frame very firmly, and then leave the jack in place so that the vehicle is held by the stands and the jack. With the vehicle held at the correct height, place the pump body so that the impellors just touch the bottom of the notch and the impellors just touch the front of the notch while the pump body is parallel to the vehicle. A gap of about 1½ inch should separate the impellor wheels and the back of the notch. It is now time to attach the pump body to the frame.

[0024] Step 9 Since any large (4 door) car or any pickup truck can be used, the exact method of attachment will change depending on the different cases. However, the same techniques will be used in all the cases: the pump body will be bolted to the frame in front of and behind the left rear wheel. With the vehicle at the correct height and the impellors just touching the bottom and front of the notch, lean the two 22 inch angle iron pieces close against the inside of the pump body a few inches from each end. Do not bolt these pieces to the pump body yet. A piece of angle iron will be bolted to the frame. Then a separate angle iron will be used to bolt this frame angle iron to these 22 inch pieces. Mark the frame opposite each of the 22-inch angle irons. If a brace or a hole or some other problem exist with the frame at this point, the 22 inch piece can be moved toward the front or toward the rear of the vehicle to avoid the problem. Remember, the 22 inch pieces have not yet been bolted to the pump body. Cut pieces of 3-inch angle iron, drill them with holes, drill the frame with holes, and bolt the pieces to the frame. Always use two or more bolts for each connection for greater stability. Use grade eight ⅜-inch bolts and grade eight locking nuts. The frame pieces should be bolted in front of and behind the left rear wheel so that angle irons can be bolted between the 22 inch pieces and the frame pieces. It is tempting to use a single piece to attach an angle iron to the 22-inch piece, and then bolt this piece to the frame. However, this requires more skill to measure and drill, and it better to use a separate piece to connect the frame angle iron to the 22-inch angle iron. With the impellors still correctly in place, measure and cut the connecting angle irons. Clamp these connecting pieces to the frame pieces with vice grip pliers. Drill and bolt these two pieces to the frame pieces, as always, using grade eight ⅜-inch bolts and nuts. Place a small 2×4 lying flat under each of the 22 inch pieces so that they are lifted 1½ inch off the ground. With the 22-inch pieces pressed against the pump body, clamp the frame-connecting piece to the 22-inch piece with vice grips. Drill and bolt each 22 inch piece to each frame-connecting piece. Now, drill through the holes in the 22-inch piece through the pump body. Use a ⅜-inch long shank drill to pass through the 5½ lumbers. Bolt these holes with grade eight 6 inch long ⅜ bolts and nuts and wide washers. Do not use lag bolts. When it is time to drive the pump on the highway, simply remove the 4 bolts and nuts holding the connecting piece to the 22 inch angle iron, secure the pump body behind the cab, remove the impellor rim, and put on a spare tire. When you get to a job site, jack up the vehicle, remove the tire, put the jack stands in place, bolt the pump body into place, and put on the impellor rim

[0025] Step 10 The hopper is simply a strong plywood box, built so as to hold the wet concrete and feed it down through a hole in the bottom into the pump. The concrete is received in a ready mixed truck and delivered into the hopper by means of a chute. The input end of the pump hose is attached to the hole in the bottom of the hopper and this hole is positioned so as to have a straight drop into the pump body. The concrete, having a slump of 6 inches, needs no aid in order to fall through the hole in the bottom of the hopper.

[0026] Since this hole will be centered over the point where the impellor wheels meet the rear of the pump body notch, it can be seen that the hopper must be positioned correctly in all three diminutions:

[0027] High enough to have the back vehicle wheels clear the bottom of the hopper when the pump is driven on the highway. Also, the top edge of the hopper must be low enough so that the concrete chute can reach it

[0028] Positioned across the vehicle so that the out put hole of the hopper hangs over the impellor-pump body point at the left rear wheel.

[0029] Likewise, the hopper must correctly set in the front and rear position so that the pump hose is squeezed between the impellors and the pump body

[0030] In order to do this, a wooden platform will be built over the back frame of the vehicle by placing a 2″×10″ timber across the frame behind the cab. If a car is being used, this is the time to enclose the cab with plywood. Moving to the rear of the vehicle, place another 2″×10″ timber across the frame as far back as possible. Continue to stack planks across the frame, behind the cab and at the rear of the vehicle until the top surfaces of these pile is at least 7 inches above the rear wheels. Bolt these planks to the frame using two bolts on both sides, in front and at the rear of the vehicle. Lay 4 more 2×10, two on each side, running from front to back, resting on the cross beams so as to support the hopper. Lay a floor of ¾ inch plywood over the plank piles. Drill holes in the plywood for the bolt heads, allowing the plywood to lay flat. Build the plywood box using ¾ inch plywood and 2×4s with a 2×10 bottom. Any strong box that can receive the concrete from the ready mix truck will function, but it is best to have the hopper trough shaped with the top open at least 2 feet and the bottom made with a 2×10. The top edge of the hopper should not be too high or the ready mix truck will have problems delivering the concrete. About six feet is best. It should be remembered that the left side of the hopper will have the concrete exit and should be lower about 6 inches. If the hopper is set level, the exit hole will not flow well. Set the hopper with the right hand side a 6 inches higher than the left hand side. The concrete will tend to flow to the hole even if the drop is not perfect Also, remember the hopper will be holding hundreds of pounds of concrete. It should be firmly braced after being bolted to the vehicle.

[0031] After the hopper is built, cut a hole 2 inches in diameter in the hopper bottom near the end of the left rear wheel side. Remember, a floor plate with a 2″ opening will be bolted over this hole on the bottom of the hopper. This should be allowed for when the site for the hole is chosen. After the hole is cut, it is easy to position the hopper so that the center of the hole is directly over the impellor wheel and the rear-notch contact point. Attach the base 2×10 of the hopper using bolts and large washers. Attach a floor plate with a 2″ threaded opening over the bottom of the hole in the hopper floor. Use bolts counter sunk into the bottom of the hopper, attaching the floor plate to the bottom of the hopper, over and covering the 2-inch hole. Thread into the opening in this plate, a 2″ female hose connector. This connector allows a 2″ hose with a 2″ male connector to be quickly attached and detached. The hopper must be high enough to allow the connections.

[0032] Step 11 The pumping hose is the simplest and most important part of this pump. The hose is designed to transfer Liquidized Petroleum Gas (Propane), has a ⅜-inch thick wall, and is rated at 350 pounds psi. It is a very strong, very rugged hose. It costs five dollars a running foot in Houston, Tex. in 2002. The hose is fitted with a male connector on each end of about a five-feet long to fit the notch in the pump body. Several such hose pieces can be outfitted as spares before the concrete pumping begins. To install or replace the hose, remove the hose retaining board from the outer side of the pump body. Put the vehicle in neutral gear and remove two of the impellor wheels. To turn the impellor rim, use a 2″×2″×8′ plank as a lever. (See photo 0005) Put the new hose in place, turning the rim as necessary. Replace the retaining board. Put the vehicle in reverse gear in order to pump concrete.

[0033] Step 12 Attach highway legal lights, license plates, etc. to the 2″×10″ planks across the back of the vehicle. (See photo 0024)