Thomson "DM" Series Electromechanical Linear Actuators for Marine Applications

Introduction

This manual provides information needed to install, troubleshoot, and repair the Thomson "DM" Series linear actuator. Please follow all instructions carefully to ensure safe, reliable operation. All stated or implied manufacturer warranties are voided if this product is not installed and operated in accordance with these instructions.

Warranty

Thomson warrants that it will repair or replace any product manufactured and sold by it which proves to be defective in material or workmanship within a period of one (1) year from the date of original purchase for consumer, commercial, or industrial use. This warranty extends only to the original purchaser and is not transferable or assignable without Thomson's prior consent. Warranty service can be obtained in the U.S.A. by returning any defective product, transportation charges prepaid, to the appropriate Thomson factory. Additional warranty information may be obtained by writing the Customer Service Department at Thomson Linear LLC, 1300 N. State St., Marengo, IL 60152, Phone: 1-540-633-3400. A purchase receipt or other proof of original purchase will be required before warranty service is rendered. Thomson's obligation under this warranty is limited to the repair or replacement of the defective product and in no event shall Thomson be liable for consequential, indirect, or incidental damages. This warranty gives you specific legal rights, and you may also have other rights which vary from state to state.

Application Notes

WARNING: Read precautions below and installation instructions before attempting to install the actuator. Disconnect battery or power source before installing or servicing the actuator. Make certain the area is clear of fuel vapors or explosive gases before beginning installation or service.

1. Actuator switch must not be installed in an area that requires ignition protection such as an engine or fuel storage compartment.
2. A 30 amp, type AGC fuse must be installed between the power source and actuator switch to protect against overcurrent. See Figure 5.
3. The ends of the actuator must be firmly mounted to withstand the required restraining torque listed in Table #1. Failure to restrain ends properly can result in personal injury or damage to nearby equipment.
4. Actuator "on time" must not exceed 25%. Example: If "on time" is 25 seconds, then the actuator must remain off for 75 seconds before being operated again. Exceeding a 25% duty cycle can lead to overheating and may result in hazardous conditions.
5. Do not submerge or install the actuator in a location that may result in the actuator becoming submerged, such as the bottom of the bilge.
6. The actuator is fully weather protected; however, it is recommended, when operating in a moist environment, that the actuator be mounted with the extension tube down to prevent moisture buildup inside the unit.
7. The actuator is factory lubricated for life and no additional lubrication is required for maintenance.
8. The actuator incorporates a slip clutch to protect against overloading. The clutch is preset at the factory to slip if the load exceeds the rated load.

Mounting

Thomson actuators are quickly and easily mounted by slipping pins through the holes on each end of the unit and into brackets on the machine frame and the load. Half-inch diameter solid pins provide maximum holding strength, and a retaining or cotter pin on each end will prevent the solid pin from falling out of its mounting bracket. Roll or spring type mounting pins should be avoided. The mounting pins must be parallel to each other, as shown in Figure 1. Pins which are not parallel to each other may cause the actuator to bind.

The load should act along the axis of the actuator, as off-center loads may cause binding. See Figure 2.

The actuator mounting brackets must be able to withstand the torque which is developed when the unit extends or retracts. See Figure 3. Restraining torque required varies with the model being used. See Table 1.

Make sure mounting pins are supported on both ends. Cantilever mounts are unacceptable. Failure to do so could shorten the life of the actuator. See Figure 4.

Electrical Connection

Wiring

Thomson DM12 linear actuators should be connected in accordance with the wiring diagram shown in Figure 5. To extend the actuator, connect red to positive (+) and yellow to negative (-). To retract the actuator, connect yellow to positive (+) and red to negative (-).

Wire Gauge Selection

Long lead wires between the power source and the actuator will result in a voltage drop for DM12 actuators. This voltage drop can be avoided by sizing the wires in accordance with the following wire gauge selection chart, which is based on a 12 VDC power source. In order to use the chart, find the point of intersection of the two known factors, such as amperage and distance, and read the required wire gauge from the curves on the chart. Example: A DM12-20A5 actuator draws 15 amps current at rated load. The intersection of the maximum current and the distance between the actuator and power source (40 feet, for example) indicates the wire gauge required (#12).

Switches

Actuator direction (forward, reverse) is controlled with a double-throw switch with the center position "off." DM12 linear actuators require double-pole, double-throw switches. McGill switch no. 0111-004, Cutler Hammer switch no. 8835-K4, or equivalent are recommended and are usually available locally. The required switch can be purchased from Thomson under part number 830-8004-016. Required switch parameters: Double-pole, double-throw; 20 amp at 28 VDC; Lever seal to keep out dirt and moisture; Center "off"; Two momentary contacts; 15/32" bushing; Screw terminals.

Connectors

Packard Electric connector 56 Series No. 2984883 and 56 Series No. 29692987 male blade are provided on DC actuators.

Troubleshooting

The chart below will be helpful for isolating malfunctions in the control system, countering difficulties with system start-up, and in troubleshooting for worn or broken mechanical or electrical components in units which have been operating for some time. For correct diagnosis, it is important to do all tests before disassembling the actuator. Electrical checks should be measured at the actuator electrical connection.

At this point, remove the actuator from the mechanism to run it by itself. Watch and listen for any changes in behavior.

Specifications

The specifications listed below apply to all actuator models covered in this manual.

The following specifications apply to individual actuator models by drive type:

Acme Screw Drive

Ball Bearing Screw Drive

The outline drawings describe acme and ball bearing screw driven actuators. All dimensions for each type are identical except for stroke and retracted lengths. The tabulated dimension charts show these lengths for each model and also describe the model numbers.

Repair Kits

Replacement parts are available for Thomson linear actuators in kit form. Descriptions of the kits, installation instructions, diagrams, and part numbers are found on the following pages. Kits are available for:

1. Cover Tubes
2. Rear Housings
3. Intermediate Gear Sets
4. Clutch Assemblies
5. Drive Screws
6. Motors
7. Front Housings
8. Seals and Gaskets

In order to obtain replacements, please contact:

THOMSON LINEAR LLC
1300 N. State St.
Marengo, IL 60152
Phone: 540-633-3400
Fax: 540-639-4162

Repair Kit Installation

Note: All screws can be replaced with standard machine screws and nuts (#12-24 and #10-32). Tighten all #12-24 screws to 70 in. lbs. upon reassembly. Tighten all #10-32 screws and nuts to 35 in. lbs.

Cover Tube

Remove 4 screws from the front housing. Slip the holder plate off the cover tube. Press the cover tube off the extension tube. Replace in reverse order.

Rear Housing

Remove 4 screws from the front housing and 1 screw from the rear housing. Pull the housing free. Insert the bumper into the hole in the rear housing. Use a thick bumper for 5:1 gearing and a thin bumper for 10:1 or 20:1 gearing. Replace in reverse order.

Intermediate Gear

Remove the rear housing as directed above. Slip the gear off of the support pin. Replace in reverse order.

Clutch

Remove the rear housing and intermediate gear. Remove the washer on top of the clutch.

ACME: Press pin out of clutch hub. Slide clutch from screw shaft.

BALL SCREW: Slide clutch from screw shaft. Remove key.

Remove the washer underneath the clutch. Two replacement washers and a replacement pin (for acme) or key (for ball screw) are supplied with each kit. Replace in reverse order.

Drive Screw

Remove the cover tube, rear housing, intermediate gear, and clutch. Slide the screw assembly (and brake if the unit is a ball screw) out of the front housing.

BALL SCREW: To reassemble, remove the clamp, slide the screw with brake back through the front housing, being careful not to lose any brake components. Tangs on the brake washer must be inserted in mating holes in the front housing prior to torquing of the bolts.

ACME: Reassemble in reverse order.

Two washers and a pin (acme) or key (ball screw) are supplied with each kit.

Motor

Seal Kit

It is advisable to replace the appropriate seals whenever the actuator is disassembled.

Seal Kit consists of: