How Are Manholes Cut?

HS-57 Manhole Saw

One of the attachments I took interest in right away when I started in this industry was the Coneqtec HS-57 Manhole Saw. I always wondered how road crews were able to get a perfect circle in the road. Well it's thanks to this attachment we have circular manholes that are flush with the road. No bumps!


The Process: 10-15 Minutes

1. You'll need to have a high flow machine. It's essential to run this attachment with the required power.
    • 45 HHP (Hydraulic Horsepower) is the minimum.
2. Attach the Hydraulic Hoses & Magnetic Control Box to power the HS-57.
    • You can hardwire the magnetic control box or plug it into the cigarette outlet in the machine
3. Line up the center of the HS-57 with the Manhole. From this point you only need to use the Magnetic Control Box. 
    • I've attached a photo below. There's only 3 switches so it's pretty self explanatory.   
    • Magnetic Control Box for HS-57
4. Once you have the HS-57 centering arms lined up with your hole. Make sure you bring the drum up so it's not touching the ground. 
    • HS57 Centering Arms
5. Once you're ready, you can start the rotation of the drum. Make sure that the machine powering the saw is turned all the way up to get the best performance.
6. As you cut through the pavement. You'll just need to hold the "Down Switch" for it to drill down and cut the manhole collar free. You won't need to use your machine's arms, unless the collar is deeper than 14".
7. Once the collar is cut free. You'll use your attachment trigger to extend the extractor arms out, so the collar is now positioned between the centering arms & clamp arms. See image below for reference.
  • An important note: The arms are not designed to push on the collar with leverage, but gravity is used. The arms are designed to get under the lip of the manhole collar.
8. Stop the rotation of the drum and bring the arms in to release the freed manhole collar.
Once the operator gets the hang of the controls, you'll be able to cut through Asphalt in about 10-15 minutes and concrete typically 20-30 minutes. The operator may still need an extra set of eyes to help position, but it's really down to a one man show with this attachment. 


Drum Sizes:

There's several different drum sizes that are offered with the HS-57. The standard diameter is 57" and should get you by with most jobs. Make sure to check the spec of your job to see what it requires and if this attachment will work for your job.

Additional Drum Diameter Teeth
24" 24 Teeth
30" 28 Teeth
40" 32 Teeth
48"  38 Teeth
57" 45 Teeth

Here's the 24" Drum (in front) compared to the standard 57"

24" Drum for Manhole Saw

Tooth Options:

There's a lot of tooth options out there so I'll try to keep this short and simple. There are 2 replaceable wear items on this attachment that need to be checked regularly. The drum itself & the teeth. 

The teeth that come standard with the drum are 14mm and fit into the block holder that is welded onto the drum. Obviously the teeth will wear over time, but so will the block holders and parts of the drum may need to be reinforced depending on the usage of the HS-57. So please, do your regular maintenance checks to keep this thing running like new!

Here's the standard Tooth & Block Holder.


Stabilizer Point:

The Stabilizer Point is an additional piece you can bolt on to the bottom in place of the clamp. It's used in a couple of circumstances. 

  1. If you have a crew, you can have your operator with the HS-57 drill the manhole out, leave the collar in the hole and go on to the next. Then you can have the rest of the crew go around with a backhoe, pipe, & chain to pull the manhole collars out of the ground. 
  2. It's also used once the road is covered with asphalt to drill the new manhole. Before the road is paved, you can mark the center of the hole with GPS coordinates. Once the road is paved over, you'll need to make a new manhole. Use your GPS coordinates to find the center and place the Stabilizer Point where you want to make the hole. 

Stabilizer Point & Pad


I had a customer in the Illinois area who's project required to go deeper than what the standard HS-57 would allow. Coneqtec offers 2 other clamp sizes that aren't as common. Apparently in China & Mongolia they have bigger manholes, so they have bigger clamps! We ordered in the Mongolian clamp and switched out the standard one. We then replaced the standard extractor arms for longer ones. This was done by taking the drum off, removing the cylinder that powers the extractors arms, and then replacing the extractor arms with the longer fabricated pieces. All in all this modification was only a few hundred extra dollars & was quite simple to do. 

Here's the standard centering arms & extractors.


All in all this attachment is really simple to use and does what it's supposed to. It cuts a circle! 


Have questions about the HS-57? Give us a call  1-888-380-6420 or send us an email


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