Pairing a mini excavator with a chain trencher gives you a compact, capable trenching machine that can work in tight spots where larger equipment just won't go. But to get the most out of this combination, you need proper setup—hydraulic connections, a correctly fitted mounting bracket, accurate depth adjustment, and correct chain tension. This guide covers the practical side of running a trencher on a mini excavator: how to configure the attachment, what to check before each job, and operating techniques that keep productivity high and wear low.
Hydraulic Connection and Setup
The chain trencher runs off the mini excavator's auxiliary hydraulic circuit—the same one that typically runs a thumb, breaker, or auger. Hooking it up means connecting the supply hose to the auxiliary outlet, and on some setups, adding a case drain line. The supply hose feeds pressurized fluid to the drive motor, which spins the cutting chain. The case drain returns low-pressure leakage oil from the motor to the tank, preventing pressure buildup that can damage motor seals. Not all mini excavators have a dedicated case drain port, so the trencher motor configuration has to match your machine's hydraulic setup.
Before you start digging, set the auxiliary relief valve to the model's specified working pressure. Both the TG-T600 and TG-T900 run at 150 to 210 bar (2175 to 3045 psi). Running the trencher at the excavator's max system pressure—which could be 250 bar or higher—can damage the motor and void the warranty. Auxiliary flow should be between 45 and 95 L/min (12 to 25 GPM) for both models. If your machine is at the high end of that range, the chain spins faster and cuts more aggressively in suitable soil. At the low end, you'll need to creep forward more slowly to let the chain cut fully without stalling.
Mounting the Attachment
The trencher mounts to the mini excavator boom in place of the bucket, using the same boom pin and linkage connections. The mounting bracket is the critical link between the attachment and the machine—it has to match your excavator's pin-to-pin spacing, pin diameter, and stick width exactly. A bracket with incorrect spacing forces the pins during installation, stressing the boom and linkage and potentially damaging the excavator. TGEC supplies custom brackets for all major mini excavator brands—just provide the make, model, pin dimensions, and stick width when you order, and we'll get you the right one.
Installation is straightforward. Pull the bucket pins (boom pin and linkage pin), align the trencher bracket with the boom and linkage holes, slide the pins in, and secure them with the correct retainers (spring clips or bolted retainers, depending on your excavator). Connect the hydraulic hoses to the auxiliary circuit and route them along the boom so they don't snag during work. If your machine has a quick coupler, the trencher bracket has to match that coupler interface, and you need to make sure the coupler is fully locked before running the attachment. Always test the trencher by running the chain at low speed for a few seconds before you start digging—check for proper rotation, leaks, and any unusual noise.
Setting Trench Depth
The depth foot at the rear of the trencher boom controls maximum trench depth by riding on the ground as the machine moves forward. Each TGEC model has three preset depth positions you select by adjusting the depth foot mounting position. The TG-T600 gives you 300, 450, and 600 mm (11.8, 17.7, 23.6 in); the TG-T900 offers 600, 750, and 900 mm (23.6, 29.5, 35.4 in). Set the depth foot to your desired position before you start, and the trencher holds that depth consistently across the whole run—no constant boom adjustments needed.
To set the depth, lower the trencher until the chain reaches the depth you want, then adjust the depth foot so it contacts the ground at that point. Lock it in place with the pins or bolts. During operation, keep the depth foot in contact with the ground—it automatically limits the chain depth. On uneven ground, you may need to make minor boom adjustments, but the preset foot gives you a reliable reference that cuts down on operator fatigue and improves trench consistency. Always measure the first section of trench before you run the whole length, because soil conditions and machine position can affect the actual depth.
Chain Tension and Maintenance
Proper chain tension is key to smooth operation and long service life. A loose chain can derail from the sprocket or idler, causing downtime and potential damage. A tight chain puts extra stress on the motor, sprocket, and idler bearings, speeding up wear and increasing the risk of bearing failure. The chain should have a slight sag when the trencher is lifted off the ground—typically 10 to 15 mm (0.4 to 0.6 in) of deflection at the midpoint of the boom. Check tension before every job, and again after the first hour of use on a new or reinstalled chain, since new chains tend to stretch a bit during break-in.
To adjust chain tension, move the idler at the bottom of the boom forward or backward using the adjustment bolts or screws. Loosen the idler lock, adjust to the right tension, and retighten the lock securely. Lubricate the chain according to the manufacturer's schedule—usually by applying chain oil or grease to the links and sprocket teeth before each use or at regular intervals during long runs. Inspect the cutting teeth daily for wear, chips, or missing carbide tips. Worn teeth cut slower and put more strain on the drive system. Replacement teeth are available and can be swapped in the field with basic tools.
Operating Techniques
Good trenching with a mini excavator comes down to a steady, controlled approach. Line up the machine at the start of the run with the tracks parallel to the direction you're going. Lower the chain into the ground at the starting point, letting it cut down until the depth foot hits the ground. Once the chain is at full depth, start moving the excavator forward slowly—walking pace—keeping the depth foot in contact with the surface. Match your forward speed to the chain's cutting capacity: in loose soil you can move faster, but in compacted or clay ground, slow down to keep the chain from stalling.
Keep engine rpm steady to maintain consistent hydraulic flow and chain speed. Avoid jerky movements or quick direction changes—they can bind the chain or push the trench off line. When you reach the end of a run, lift the trencher out of the ground before stopping or repositioning. For turns or direction changes, lift the chain clear, reposition the machine, and lower it back in at the new starting point. Never try to turn the machine while the chain is still in the ground—that's a quick way to bend the boom or damage the chain and sprocket.
Common Setup Issues and Solutions
A few common problems pop up when setting up a mini excavator with a trencher. If the chain runs too slow or stalls under load, the usual culprit is low hydraulic flow. Check that the auxiliary circuit is delivering the required 45 to 95 L/min, and slow down your forward travel to match the available flow. If the hydraulic system overheats during extended use, flow might be too high for the motor, or the relief valve could be set too high. Check the relief pressure setting and make sure the hydraulic oil cooler is working properly.
If trench depth is inconsistent, make sure the depth foot is securely locked and that the operator is keeping it in contact with the ground. On uneven terrain, you may need to make small boom adjustments to maintain depth. If the trench is wider than expected, check that the correct cutting width is installed and that the chain isn't wandering due to improper tension or a worn idler. If the excavator feels unstable during trenching, the trencher might be too big for the machine, or the ground under the tracks might be soft or uneven. Verify that the trencher model matches your excavator's weight class, and make sure the machine is on firm, level ground.
Getting the Most From the Setup
A properly set up mini excavator and chain trencher is a productive, versatile system for residential utility, irrigation, drainage, and landscaping work. The key pieces are: matching the trencher to your excavator's hydraulic output and weight class, installing the right mounting bracket, setting the relief pressure to spec, adjusting chain tension correctly, and operating with steady forward speed and consistent depth foot contact. Get those right, and the system will dig clean, consistent trenches in a fraction of the time it would take with a bucket—with less surface disturbance and less backfill.
The TGEC excavator chain trencher is available as the TG-T600 for 2.5 to 5 ton mini excavators and the TG-T900 for 3 to 7 ton machines, both with custom mounting brackets and full technical support for setup and installation. For help choosing between these models for your specific mini excavator, see our mini excavator trencher selection guide.
