MKS LDS Kit for the HV6120 Servo

A High Performance LDS (linear drive system) for the MKS HV6120 servo.

I would have zero qualms installing this LDS system in a dynamic soaring ship (many folks already have and with great success); anything else will be a walk in the park for this system.

The servo trays have an outboard ball bearing that helps to carry the servo shaft loads and greatly reduces servo play. The unique servo arm is designed so that it has tons of clearance, no more grinding your clevis' for maximum throw. The servo arm then connects to a strong control rod which connects to a double carbon fork epoxied inside of the control surface, this results in massive throws while the whole system is contained within the wing. Aerodynamically clean and slop free.

There are a number of ratios available. As the builder you will need to make your own decision as to which ratio to choose. The different ratios are presented like this for example: 6.35mm / 5.83mm. The first number 6.35mm is the "servo arm length" which is the distance from the center of the servo output shaft to the hole in the servo arm. The second number 5.83mm is the "control horn height" which in this case is the distance from the bottom of the horn to the connecting rod hole.

Studying the parts kit, you will find exceptionally well machined components; the CNC parts are beautiful, the anodizing is clean, resulting in a very good fit and finish. The kit is well thought out and very complete (even includes sand paper and super glue for assembly). You are given a choice for your pushrod assembly, you can use the included carbon rods to create exact length push rods or you can make adjustable length pushrods using the included threaded rod. The designer has proven that the carbon pushrod assembled using super glue can withstand 220lbs in tension. The servo frame parts are machined from 3.5mm thick carbon and the control horns are machined from 1.7mm carbon. Beefy stuff.

Another aspect of these servo frames that we liked is that they will fit into smaller servo pockets than other larger servo frames in this class. The servo pushrods are connected to the servo drive and control horn using machined pins that accept e-clips at both ends for retention. The kit includes extra e-clips in case some get lost. FYI, the designer has created an e-clip installation tool to make it much easier to install the clips. I have used it and it works very well. On the other hand removing them will require some patience.

Below is a video you can watch to learn how these kits are assembled. The kits have been improved since the video was made so you will notice some discrepancies between the video and the kit, parts-wise. The video is still relevant for learning how to assemble the system.

Note: The 6.5mm servo horns have two drive holes. One at 3mm and one at 6.5mm from the center of the the servo drive shaft. The 2.5mm horn only has the one hole at 2.5mm.

What comes in the kit: 

• D2.5*49mm Threaded Push Rods *2
• Dual Servo Horns
• Servo Frame*2
• Ø1.3*8mm Stainless Steel Pins*2
• Ø1.3*8.5mm Stainless Steel Pins*2
• E-clips*4
• M1.6*5 Screws*4
• Aluminum Connectors 4*4*21.6mm*4
• Optional Control horns*4 pieces

Features:

• Works with MKS HV6120 servos
• Anodized Aluminum Alloy Surfaces
• The linkage and servo arm are designed so that the maximum servo travel can be used
• Precise fitting and slop-free servo arms 
• Optimal power transmission possible