Hydraulic Torque Wrench Safety and Operation

Before operating a hydraulic torque wrench

Hydraulic torque wrench safety begins with really understanding what a hydraulic torque wrench is and how it is used.

In contrast to hydraulic tensioning devices which directly stretch a bolt, hydraulic torque wrenches apply a turning force or torque to a nut or bolt head.

This force causes the bolt thread to advance forward for tightening, and backward for loosening.

This Wikipedia community defines a hydraulic torque wrench as the following:

what is a hydraulic torque wrench anyway

Who is this written for:

If you are reading about hydraulic torque wrench safety and operation as part of a ASTM training exercise, or workplace requirement, I encourage you to continue reading to the very end.

There is a ton of information about hydraulic torque wrench safety which I assure you will find valuable.

However, putting together a comprehensive and very informative article about hydraulic torque wrench safety and operation has created a very long article.

In the interest of time, if you are a safety managers looking for ten minute or less definitive guide to operating a hydraulic torque wrench safely, we created this compilation video for you.

A complete hydraulic torque wrench system

I think you would agree, that by itself a hydraulic torque wrench is pretty much an expensive and useless tool.

However, aided by a hydraulic torque pump, also known as a hydraulic power pack unit which is connected to the hydraulic torque wrench via hydraulic hoses and fittings creates a powerful and accurate fastening tool system.

This system allows the hydraulic torque wrench to fulfill its designed purpose of tightening and/or loosening fasteners, which require large amounts of force quickly.

In doing so, a complete hydraulic torque wrench system will achieve the proper pre-load.

Two primary types of hydraulic torque wrenches

There are actually six types of hydraulic bolting tools.

Types of hydraulic torque wrench for precision boltings

However, only two of them are commonly used across nearly every industrial vertical.

They are as follows:

The “square drive hydraulic torque wrench” which uses impact sockets.

And, the “low clearance” or “low profile cassette hydraulic wrench”, which utilizes interchangeable “hex links” which are secured unto the hydraulic torque wrench cassettes with a pin.

SAFETY TIPS #1: Hydraulic torque wrench systems vary so it is important to always review the specific operating instructions provided by the manufacturer of the torque tool you are using.

Now, let us take a look at these two types of hydraulic torque wrenches individually.

Square Drive Hydraulic Torque Wrenches

Hydraulic Torque Wrench

One of the most basic, yet highly innovative and popular square drive tools is the Torc TTX hydraulic torque wrench.

The TTX is an example of a hydraulic torque wrench that uses an impact socket that fits on the nut or bolt head.

This square drive tools has a swivel that features multi-position hose couplers.

The TTX hydraulic torque wrench swivel rotates 360 degrees to ensure zero hydraulic hose interference.

It can also be manufactured with a swivel which turns 180 degrees along with 360 degrees.

Multi-purpose hose swivel of hydraulic torque wrench

The Torc TTX Square Drive is comprised of various models which offer a broad torque range from 105 ft.lbs. to 20750 ft.lbs.

The square drive torque wrench is accurate to plus or minus 3%.

This TTX hydraulic torque wrench is manufactured with 70-75 grade aluminum alloy which is both extremely durable and lightweight.

TTX Hydraulic Torque Wrench Chart Dimensions

As illustrated in the image above, the TTX square drive consists of only three moving parts.

It features an innovative push through square drive, which makes it extremely easy to switch from tightening or loosening any bolt.

This square drive wrench features a 360 degree adjustable rear reaction arm which has a push button to engage, and disengage the arm.

Hydraulic Torque Wrench Safety by Design


Square drive hydraulic wrenches like the TTX use a reaction arm that can be rotated to a secure position.

SAFETY TIP #2: You always want to adjust the reaction arm so that it is braced firmly against the structure being fastened.

Low Profile / Low Clearance Hydraulic Torque Wrench

Hydraulic Torque Wrench Types For Bolt Tightening Solutions TTZ Hydraulic Torque Wrench - TORC Limited Clearance Fastening - Controlled Tightening Tool


Now, let us look at how to correctly operate the TTZ hydraulic torque wrench.

Hydraulic Torque Wrench TTZ

The TTZ hydraulic torque wrench has several industry names. These included:

  • Low profile wrench
  • Cassette torque wrench
  • Limited clearance hydraulic wrench
  • Low clearance torque tool

If you know another other jargon for cassette torque wrench tools, please comment below, or post it on the AMG Bolting Solutions Facebook page.

Regardless, of what you choose to call it, the TTZ low profile htdraulic torque wrench comes in various dimensions and achieve unique ft. lbs. based on unit size.

TORC TTZ Limted Cleareance Hydraulic Torque Wrench Specs - AMG Bolting Solutions

Safe Operation of the TTZ limited clearance hydraulic wrench.

First, you want to inspect your hoses and secured them to the unit and pump.

You want to ensure that your hex link is secured in place with the link pin.

Once these safety checks are complete, you may place the low profile hydraulic torque wrench unit over the bolt stud and unto the nut.


  • The torque applied to the fastener depends on the pressure developed by the torque power pump. Therefore, power pump pressure must be adjusted to provide the proper torque value.

A typical torque table can apply to several wrench models.

In the video demonstration, the Model TWLC -2 torque pump is used.

Below, we discuss hydraulic power pump in more detail.

According to the torque table chart the bolt torque range is 600 to 650 foot pounds of pressure.

I recommended torque pressure of 4000 psi will exert 630 foot-pounds of torque at wrench hex link.

hydraulic torque power pump chart

You will most likely need to adjust the power pumps pressure.

Before doing so, be certain that the hydraulic torque wrench system is fully connected.

Once you have verified that every component is safely connected, turned on the pump switch.

As a safety feature, the you will need to press the “run” button to start the pump, and then you’ll need to press and hold the “set” button.

While holding down the “set” button, turn the adjustment knob until the hydraulic pump’s gauge displays the correct amount of pressure.

You may now release the “set” button on the hydraulic torque pump.

Sometimes a hydraulic torque wrench will move around while you adjust the torque pump settings, so ensure your fastening tool is fully seated to reaction off of a solid point.

TTZ Hydraulic Torque Wrench - Reaction Point

Most low clearance torque wrenches are designed with a reaction pad to brace against an adjacent nut.

SAFETY TIP #3:  Whenever it is possible the built by design reaction pad of your limited clearance hydraulic toque wrench should rest of the flat side of a nut, and not a corner.

Now, with your pump set to the accurate pressure and all safety checkpoints reviewed, you may engage the hydraulic power pump by holding down the “run” button.

In an instant the power pump unit will pressurize allowing the hex link on your hydraulic wrench to rotate.

As the hydraulic torque wrench reaches completion of a fastening stroke, you need to briefly release the “run” and then quickly press it again to began another fastening stoke.

Loosening a nut with a low profile hydraulic torque wrench

To reverse, or loosen a nut you need to flip your cassette torque wrench tool over and repeat your safety checks.

You will want to ensure the reaction arm has a solid point to react off of prior to re-engaging the pump.

As always, make certain that your hands are free from the unit and the hydraulic hoses at all times while pressurizing the hydraulic torque wrench via the power pump.

If you are interesting in buying a TTZ hydraulic torque wrench, you can contact AMG Bolting Solutions directly for a torque tool quote, download our price list, visit our eBay store, or shop at one of our partner site like Global Industrial.

AMG Bolting Solutions - Low Clearance Hydraulic Torque Wrench

6 Types Of Hydraulic Torque Power Pumps

More details coming soon!

Safely Operating A Hydraulic Power Pack Unit

You need to ensure that your hydraulic hoses are correctly hooked up to the unit.

The couplers must be fully screwed on for the units operate.

In addition, you will want to ensure that your hydraulic hoses are correctly hooked up to your hydraulic torque pump.

Once you do this, you can place your hydraulic torque wrench unit on the nut.

Again thinking of safety, you will want to adjust the reaction arm and make certain your hydraulic square drive tools has a solid point to push against as force is applied.

As is always the case, make sure the hydraulic hose is completely out of the way.

Prior to engaging the hydraulic torque pump which powers the system, inspect all components for damage.

Fully inspect the hoses.

Dirt and debris in the hydraulic torque wrench system may cause damage to the hydraulic pump, the valves, or the torque wrench. For this reason, make sure that the fittings are clean.

Also, ensure the fitting are tightly in place. Loose fittings have been known to leak, and in some case burst.

Remember, if a leak occurs shut off the pump and depressurized the system.

Never grasp a leaking hose. The pressurized fluid may cause serious injury.

During operation stand clear of the hydraulic hoses and torque wrench system to ensure safety.

To begin tightening engage the hydraulic power pump.

Ratchet the wrench with several cycles until it stalls at the preset pressure.

Your nut will be tightened hands-free.

Operating your hydraulic torque pump with your torque wrench

It is recommended that you operate the TTX and TTZ with a hydraulic torque pump that delivers up to 10,000 PSI.

First ensure there is adequate hydraulic fluid in the reservoir checking the viewing windows.

You should see hydraulic fluid in both viewing windows.

If there is an adequate amount, unscrew the knob labeled oil and insert the recommended Azolla hydraulic fluid until the reservoir is completely full.

Make sure that the pump is in the off position, and that the system is depressurized.

Then, connect and tighten the hoses.

The main switch which is located next to the motor is what controls all power to the hydraulic pump system.

It must be turned to the “ON” position for operation.

The pendant houses a three-position rocker switch and a momentary push button.

By pressing on the “RUN” side of the rocker, you will starts the pump and send pressure to the hydraulic torque wrench for tightening or loosening.

The rocker must be held in this position since it is spring loaded to the center.

The center position releases pressure and retracts the wrench piston causing the wrench head to Ratchet back for the next torque cycle.

The pump is running when the switch is in the center position.

The “STOP” position turns off the pump.

The SET button is used when adjusting pump pressure.

You must set to the hydraulic power pack to the predetermined psi to achieve your desired torque.

It is highly recommended that you refer to the torque chart for the necessary psi.

To set the pressure amount of pressure, turn the pump on and loosen the wing nut.

Next, turn your pressure knob until you achieve your desired level.

Once you achieve your desired psi level secure the wing nut.

SAFETY TIP #3: Tightening the wind nut prevent the PSI from changing.

Now, run the pump several times to ensure the desired psi is achieved.

To loosen a fastener, you can make a quick change from tigthening to loosening with the TTX’s innovative push through square drive.

Now, simply place your square drive tool back on the socket to ensure your reaction arm has a solid point to react off of which is free of the hoses.

To guaranteed you have sufficient power to loosen a nut set your pump to 10,000 psi.

Next, actuate your pump and began ratcheting.

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