Chicago Pneumatic Backfill Tampers and Air Rammers
Three air tampers for compacting backfill in trenches, around pipe and against structures, $1,212 to $1,470. 18 to 38.5 CFM, 30 to 42 lb, and butt sizes from 2-1/2 to 6-1/4 in. plus iron pole butts.
The short version
A backfill tamper is the tool for the places a plate compactor cannot reach — the bottom of a narrow trench, the haunch under a pipe, up against a foundation wall or a manhole, and any confined space where you still need the fill compacted properly. Pick on butt size and trench width: the CP 0003 at 30 lb, 18 CFM and a 5 in. butt is the narrow-trench tool and the lowest air draw of any Chicago Pneumatic tool we sell; the CP 0004 at 42 lb with a 6-1/4 in. butt covers the most ground per pass; the CP 0035 sits between them and is the only one in the line with a built-in muffler. All three run an integral oiler, so they lubricate themselves as they work.
The CP Backfill Tamper Line
Three tools, all with a 1/2 in. NPT air inlet and an integral oiler that lubricates the tool continuously while it runs. What separates them is bore and stroke, valve type, weight and the size of the butt on the bottom.
CP 0004 Pneumatic Backfill Tamper
The heavy tamper. A 2-1/4 x 6 in. ring-valve piston driving a 6-1/4 in. aluminium butt at 780 blows a minute, 42 lb and 50 in. long. It ships with a 90 degree angle air inlet, and it covers more ground per pass than anything else in the line.
28 CFM at 90 psi · 780 BPM · 42 lb · 50 in. · 2-1/4 x 6 in. bore and stroke · ring valve · 1/2 in. NPT inlet
CP 0035 Pneumatic Backfill Tamper
The only tamper in the line with a built-in muffler, so there is nothing to add and nothing to lose. A 1-1/2 x 5-1/2 in. simplate-valve piston at 800 blows a minute, 36 lb and 48-1/4 in. long, shipping with a 6 in. iron butt.
38.5 CFM at 90 psi · 800 BPM · 36 lb · 48-1/4 in. · 1-1/2 x 5-1/2 in. bore and stroke · simplate valve · built-in muffler
CP 0003 Pneumatic Backfill Tamper
The light tamper, and the one that fits a narrow trench. 30 lb, 52 in. long and only 18 CFM — the lowest air draw of any CP tool on this site, so it will run alongside another tool on a small compressor. Ships with a 5 in. aluminium butt.
18 CFM at 90 psi · 800 BPM · 30 lb · 52 in. · simplate valve · 7/8 in. piston rod · 1/2 in. NPT inlet
Compare All Three Tampers
Factory figures from the Chicago Pneumatic tamper datasheet, measured at 90 psi. Air consumption figures include the butt each tool ships with.
| Model | Part no. | Valve | Bore and stroke | Blows/min | Air at 90 psi | Weight | Length | Air inlet | Butt supplied | Price |
|---|---|---|---|---|---|---|---|---|---|---|
| CP 0003 | 8900 0040 06 | Simplate | 1-7/16 x 6 in. | 800 | 18 CFM | 30 lb | 52 in. | 1/2 in. NPT | 5 in. aluminium (P 089008) | $1,231 |
| CP 0035 | 9246 0205 05 | Simplate | 1-1/2 x 5-1/2 in. | 800 | 38.5 CFM | 36 lb | 48-1/4 in. | 1/2 in. NPT | 6 in. iron (9245 9981 60) | $1,212 |
| CP 0004 | 8900 0040 02 | Ring | 2-1/4 x 6 in. | 780 | 28 CFM | 42 lb | 50 in. | 1/2 in. NPT, 90 degree angle | 6-1/4 in. aluminium (P 089050) | $1,470 |
Swipe the table sideways to see every column.
The air figures are not in the order you would expect. The heaviest tamper, the 42 lb CP 0004, draws 28 CFM. The lighter 36 lb CP 0035 draws 38.5 CFM, the most in the line. That is the valve: the CP 0004 uses a ring valve on a 2-1/4 in. bore, while the CP 0035 uses a simplate valve on a 1-1/2 in. bore and moves more air to do less work per blow. If you are tight on compressor capacity, the CP 0003 at 18 CFM is the one to take.
The CP 0035 is the only tamper here with a built-in muffler, so there is nothing to bolt on and nothing to lose off the back of a truck. The CP 0003 and CP 0004 take add-on mufflers P 126126 and P 125807 respectively.
Tamper Butts and Mufflers
The butt is the plate on the bottom of the tamper, and it is what decides how much ground you cover per pass and how hard you can hit. Aluminium butts are lighter and easier on the operator; iron butts last longer in abrasive fill. Pole butts are a different shape entirely, for driving and for compacting around posts.
| Diameter | Material | CP 0003 | CP 0004RV | CP 0035 |
|---|---|---|---|---|
| 2-1/2 in. | Aluminium | — | P 138879 | — |
| 3 in. | Aluminium | — | — | 9245 9987 21 |
| 4 in. | Aluminium | — | — | 9245 9990 28 |
| 5 in. | Aluminium | P 089008 | — | — |
| 6-1/4 in. | Aluminium | — | P 089050 | — |
| 6 in. | Iron | 3303 0050 82 | 3303 0050 81 | 9245 9981 60 |
| Pole butt | Iron | 3303 0050 84 | 3303 0050 83 | 9245 9981 65 |
Swipe the table sideways to see every column.
Mufflers
| Model | Muffler part no. | Notes |
|---|---|---|
| CP 0003 | P 126126 | Add-on. |
| CP 0004RV | P 125807 | Add-on. |
| CP 0035 | — | Built in. Nothing to order. |
Butt size is the real specification. A 2-1/2 in. butt on a CP 0004 turns a wide-coverage tamper into a tool that will get into the haunch under a pipe. A 6 in. iron butt on a CP 0003 turns the light narrow-trench tool into something that covers ground. Both are one bolt-on part away, so it is worth buying a second butt with the tool rather than a second tamper later.
Aluminium or iron. Aluminium is the default: lighter on the wrist and easier to swing all day. Iron lasts far longer in rock, recycled concrete and other abrasive backfill, at the cost of weight. If the fill is anything harder than sand or clean soil, buy the iron butt.
What Compressor You Need Behind Them
Air consumption at 90 psi with the tamper running continuously. Tampers are cheap on air compared with breakers and rock drills, which makes them the natural second tool on a jobsite compressor.
| What is running | Total draw | Compressor | Notes |
|---|---|---|---|
| One CP 0003 | 18 CFM | CPS 110 (95 CFM) | The lowest air draw of any CP tool we sell. Runs alongside almost anything. |
| One CP 0004 | 28 CFM | CPS 110 (95 CFM) | Under a third of the machine. |
| One CP 0035 | 38.5 CFM | CPS 110 (95 CFM) | The thirstiest tamper in the line, still comfortable on a 110. |
| A CP 1260 breaker plus a CP 0003 | 63 + 18 CFM | CPS 110 (95 CFM) | Break out, dig, backfill and compact off one machine. The classic utility setup. |
| Two tampers plus a breaker | 100 to 140 CFM | CPS 185 (180 CFM) | A full trench crew on one compressor. |
Swipe the table sideways to see every column.
Getting Compaction That Actually Passes
A tamper is only as good as the lifts you put under it. These are the practical points that decide whether a trench passes a compaction test the first time.
Compact in lifts, not in one go
Six to eight inches of loose fill at a time is the usual rule, less in heavy clay. Dump three feet in and run the tamper over the top and you will compact the top four inches and leave the rest to settle under the road later.
Moisture content does most of the work
Fill that is too dry will not bind no matter how long you stand on it, and fill that is saturated will pump. If the material balls in your hand and holds together without water showing, it is about right.
Overlap the passes
Work the butt across the trench in overlapping passes rather than punching the same spot repeatedly. On a 5 in. butt in a 24 in. trench that is five passes across, then advance one butt width and repeat.
Get into the haunch
Under and beside a pipe is where compaction actually matters and where a plate compactor cannot go. A small butt on a tamper is the only practical way to compact the haunch properly, and it is the difference between a pipe that holds grade and one that sags.
Let the tool do the work
The tamper weighs 30 to 42 lb for a reason. Guide it and let its own weight plus 780 to 800 blows a minute compact the fill. Leaning on it does not compact faster and will wear you out by mid-morning.
Keep the air dry
These tools carry an integral oiler that lubricates them continuously, so there is no separate lubricator to remember. What they do not have is a water trap. Put a water separator at the compressor and the oiler can do its job.
Chicago Pneumatic Backfill Tamper FAQ
What is a pneumatic backfill tamper used for?
A backfill tamper, sometimes called an air rammer or a pneumatic tamper, compacts fill material in places a plate compactor or a jumping jack cannot reach: narrow trenches, the haunch under and beside a pipe, up against foundation walls, around manholes and posts, and inside any confined excavation. It drives a flat butt into the fill at 780 to 800 blows a minute using compressed air.
Which Chicago Pneumatic tamper should I buy?
Pick on trench width and butt size. The CP 0003 at 30 lb, 18 CFM and 52 in. long with a 5 in. aluminium butt is the narrow-trench tool and the easiest on a small compressor. The CP 0004 at 42 lb with a 6-1/4 in. butt covers the most ground per pass and is the choice for wide trenches and general backfill. The CP 0035 at 36 lb sits between them and is the only model with a built-in muffler.
What size compressor do I need for a pneumatic tamper?
Very little by construction-tool standards. The CP 0003 draws 18 CFM, the CP 0004 28 CFM and the CP 0035 38.5 CFM at 90 psi. Any of the three will run off a CPS 110 at 95 CFM alongside a 60 lb paving breaker, which is why a tamper is usually the second tool on a utility crew’s compressor rather than the reason for buying one.
What size tamper butts are available?
Aluminium butts in 2-1/2, 3, 4, 5 and 6-1/4 in., 6 in. iron butts, and iron pole butts, depending on the model. The CP 0003 takes the 5 in. aluminium (P 089008), 6 in. iron (3303 0050 82) and pole butt (3303 0050 84). The CP 0004RV takes 2-1/2 in. aluminium (P 138879), 6-1/4 in. aluminium (P 089050), 6 in. iron (3303 0050 81) and pole butt (3303 0050 83). The CP 0035 takes 3 in. (9245 9987 21), 4 in. (9245 9990 28), 6 in. iron (9245 9981 60) and pole butt (9245 9981 65).
Aluminium or iron butt?
Aluminium is lighter and easier on the operator over a full shift, and it is what all three tampers ship with except the CP 0035. Iron lasts considerably longer in abrasive fill such as crushed rock or recycled concrete. If the material is anything harder than sand or clean soil, buy the iron butt and expect to swing a bit more weight.
Do CP tampers need an in-line lubricator?
No. All three carry an integral oiler that lubricates the tool continuously while it runs, so there is no separate lubricator to fit or remember to fill. They do still benefit from a water separator at the compressor, because water in the line will wash the oil off the working parts.
Which tamper is the quietest?
The CP 0035, which is the only model in the line with a muffler built in. The CP 0003 and CP 0004 take add-on mufflers, part numbers P 126126 and P 125807. On a job with a noise ordinance, or anywhere working near occupied buildings, order the muffler with the tool.
How thick a lift can a pneumatic tamper compact?
Six to eight inches of loose fill per lift is the usual working figure, less in heavy clay and more in clean granular material. Compaction requirements are set by the specification on your job, so check what the engineer has called for. What is certain is that dumping a trench full and tamping the top will not pass a test.
Do you stock these?
Yes. All three models and the full range of butts ship the same day on orders placed by 4 PM Eastern. Add one to the cart above, or call 1-888-883-5144 to have a spare butt or a muffler put together with the tool.
Tampers and butts in stock
Tell us the trench width and the backfill material and we will match the tamper and the butt. Same day shipping on everything on this page.