More and more chiropractors are using the segmental drop adjusting table to care for their patients. Learn the history and workings of this important equipment

When I visited a table factory, I asked the engineers and designers how they came up with the drop mechanisms. In some cases, I was able to interview those who were interested in the design and development of tables and those selling drop-style tables. In all cases, there was one theme that was quite prevalent—that was that more and more doctors are using drop tables to adjust their patients.

When I lecture about the Thompson Technique across the country, there are two questions that are always asked at every seminar: How does the drop mechanism work? How did it get started?

So how does the drop mechanism work? First, there are some basic structures that are used to control the dropping of the cushion that supports the body. Most drop tables that utilize a drop mechanism must have several controls for the drop adjusting system. There must be a cocking mechanism that can be either manual, air, hydraulic, or even a magnet and drop system.

Figure 1

The very first commercially built table that used the drop headpiece was a side posture toggle recoil adjusting table used by BJ Palmer in the classroom (Figure 1). This particular table has a magnet to hold the cocked headpiece in place until the adjustive thrust is delivered. These tables have been used in the classroom for generations and are still functioning today at Palmer College of Chiropractic, Davenport, Iowa.

Figure 2

Eventually, various methods were tried that would control the depth of the drop mechanism and the quickness of the drop as the thrust was delivered to the segment being adjusted. The first fully functional drop table was developed in the Quad Cities in East Moline, Ill. The first 17 tables that were sold had the manual cocking mechanism operated by stepping on the foot plate to create the raising of the cushion on which the patient was laying (Figure 2).

J. Clay Thompson,DC, developer of the Thompson Technique, worked for the government during World War II at the Rock Island Arsenal, and had developed knowledge of working with metal and machining. This background proved beneficial in his development and design not only of the original head piece, but in the design of the full drop table.

As Thompson would tell the story, after a short time, the new cocking mechanisms “gaulded,” which is a technical term used to describe metallic surfaces that would stick and render the mechanism useless. After much agonizing and many late hours, they finally came up with a mechanism that would function properly. The new units were taken to the doctor’s offices where the defective units were replaced.

Figure 3

The first drop adjusting tables had manual cocking. The premise that using the drop would enhance the adjusting procedure has been borne out over the decades by its use in the chiropractic profession. The original drop pieces were added to the basic frames of the hylo tables being manufactured at that time (Figure 3).

It was in the mid-1950s that Thompson began development of additional drop pieces for the dorsal, lumbar, and pelvic regions to expand on the adjusting of the entire spine with this new method of correcting subluxations of the spine. Within a short time after development of the basic drop table, Thompson and his attorney, Judge Bush, went to Washington, DC, to appear before the Patent Commission. His original patent application had been turned down several times, and he and the Judge were summoned to appear before the appeals committee. Within 3 weeks after the hearing, the patent was issued to Thompson by the Patent Appeals Committee. Shortly afterward, he licensed the patent to the Williams Manufacturing Co to produce the Thompson Table.

The drop table has evolved through many adaptations and numerous changes to what it is today. Primarily, the drop mechanism is at ½ to 5/8 of an inch for most tables, although there are some variations that may be found.

Figure 4

One of the changes in the drop mechanism involved the adaptation of bearings added to the inside of the piston tube used to cock the drop piece. This tube has several rows of ball bearings aligned vertically inside of the tube to increase the speed of the drop (Figure 4).

Figure 5

The older, solid piston type rides up and down as the cocking mechanism is engaged and affords an increase in the speed of the drop over the original greased piston (Figure 5). The vertical bearings are encased in the housing around the entire mechanism. This style of drop has been used for a number of years.

Figure 6

On some tables, another type of drop is known as the “notched wedge” or “T-Bar” drop mechanism. The tension mechanism is the horizontal tube contains a spring and ball bearing. The bearing rides in the notch of the wedge or T of the drop mechanism. The tension is applied by turning the knob into the tube that increases the tension of the ball bearing in the notch (Figure 6). This is what governs the variation of pressure needed to set the drop according to the weight of the patient. This precise control is the basis for achieving the proper adjustment.

Figure 7

The tension is adjusted by turning the control knob in to increase tension and out to reduce tension on the drop piece (Figure 7). This control is the most important consideration in setting up the drop piece to the weight of each patient. Keeping the drop tension at the minimum creates the most ideal situation of the adjusting process with thes egmental drop system.

Figure 8

The T-Bar drop is attached to the base of the cushion. By the very nature of the width of the T attachment, it will provide a controlled drop with the thrust even out to the edge of the cushion (Figure 8).

The modifications that have been made by various manufacturers has improved the quality of the adjusting process in using a low-force adjusting for our patients.

Segmental drop adjusting affords the opportunity for the doctor of chiropractic to adjust the patients with reduced reflective force to the doctor. It is physically easier, especially for doctors to adjust patients who are larger than they are. CP

Wayne Henry Zemelka, DC, practices in Davenport, Iowa, at the Zemelka Family Chiropractic Center and teaches at Palmer College of Chiropractic. He is certified in video motion x-ray (videofluoroscopy) and the Thompson Technique, which he studied under the tutelage of J. Clay Thompson, DC. He has also written a Thompson Technique Manual and video. Zemelka can be reached at: drwayne@netins.net; www.drzemelka.com.