The issue in this case is which of two successive employers is responsible for compensation for claimant’s back condition. Both denied compensability. The first employer, Fred J. Early Company (Early), contended that the back problem was not the result of an injury incurred during employment with the company. The second, Donald Drake Company (Drake), claimed that the condition resulted from a pre-existing back problem. The referee characterized the condition as an injury incurred during the first employment and held Early responsible. The Board found that the condition was an occupational disease and, applying the “last injurious exposure” rule, held Drake responsible.
Neither party contends here that claimant’s back condition is anything other than an occupational disease. Both parties argue about the proper application of the “last injurious exposure” rule.1 Nevertheless, whether it was proper to apply the rule to hold Drake responsible depends on whether claimant’s condition was an injury or a disease. Boise Cascade Corp. v. Starbuck, 61 Or App 631, 659 P2d 424 (1983). Unlike the situation in United Pacific Ins. v. Harris, 63 Or App 256, 663 P2d 1307 (1983), where the referee and the Board both treated the claim as involving an occupational disease, and no party challenged that characterization in this court, the Board here rejected the referee’s injury characterization. The nature of the claim is decisive.
Claimant, 31 years old, had worked for eight years as an “operating engineer” before beginning work for Early on *264January 21, 1980. He had had no previous back problems. At Early, half of his work day consisted of operating a front-end loader to scoop up materials and “ram” them into a pile. The remainder involved operating a crane and doing light manual lifting. He testified that operation of the loader required “constant turning and moving and back and forth balancing.”2 He said that after two or three weeks he started having trouble with the transmission on the loader and, when he attempted to change directions with the machine, it would “instantaneously] grab” as if he were “driving into a brick wall,” causing a “terrific shock” that was “really affecting [him].” At the same time the loader’s transmission troubles began, claimant also began to have neck and back pains. He said that he had complained about the pain to other employes. He continued operating the loader throughout his employment with Early, and his back pains grew progressively worse. He was fired on March 3,1980, for tipping over a crane that he was operating without safety cantilevers.
Claimant was unemployed for about a week. During that time, his pain “seemed to kind of relieve itself a bit” but did not go away. Nevertheless, he called his union and said he was ready to go to another job. On March 12,1980, he began a three-day job with Drake that involved running front-end loaders similar to the one at Early, but larger and more smooth running. They had no transmission problems. They bounced when he drove over potholes, but he said that the road conditions were the same at both jobs. He testified that, after two nine-hour work days at Drake, he could not stand the pain any longer and did not return to work.
Claimant was diagnosed as having “thoraco-cervical strain with attendant mild myofascitis.” He was seen twice by Dr. Ebert, who reported:
“The [patient’s] medical condition is clearly related to his employment in February of 1980. The 2 days which he worked subsequently for Donald M. Drake only resulted in temporary symptomatic worsening.”
He was also seen by Dr. Pasquesi, who concluded:
*265“In my opinion, this patient has an occupational disease, which admittedly was becoming worse for a month or so prior to leaving his employment before working for the Donald M. Drake Company and made worse by the work at the Donald M. Drake Company.
“From a medical standpoint, both conditions are applicable as far as responsibility of his symptoms and having to lay off work, but the patient was having increasing symptoms before working the last two days at the Donald M. Drake Company. He admittedly became worse at the Donald M. Drake employment.”
On March 14,1980, claimant filed a claim with Drake, describing his “injury” as “[d]riving the loader jolted me too much, creating pain in neck and back.”
He indicated the date or hour of injury was “All day” on March 13,1980. On April 9,1980, he also filed a claim with Early, stating, “I was operating heavy equipment, front end loader, and it caused back and neck to hurt,” which occurred in February, 1980.
The referee found:
“* * * [Claimant's employment at Fred J. Early Co. in operating the old loader to have placed sufficient strain on his body to cause his injuries to his neck and back. This conclusion is supported by Drs. Ebert and Pasquesi * * *. Claimant’s subsequent difficulty while at Donald M. Drake Co. was not a new injury but a worsening of claimant’s injury which he received while at Fred J. Early Co.”
The Board disagreed. It found that
“* * * under the standards of James v. SAIF, 290 Or 343, 348 (1980), claimant has an occupational disease. In such a situation, the most recent employer is responsible under the last injurious exposure rule if that employment environment ‘could have’ contributed to the disease. Inkley v. Forest Fiber Products Co., 288 Or 337, 344 (1980). From Dr. Pasquesi’s opinion that claimant’s work for the second employer, Drake, did worsen his condition, it rather easily follows that claimant’s work at Drake could have contributed to the disease and Drake is responsible.” (Emphasis is the Board’s.)
In James v. SAIF, 290 Or 343, 624 P2d 565 (1980), the Supreme Court approved the distinction made between “injury” and “disease” in O’Neal v. Sisters of Providence, 22 Or *266App 9, 537 P2d 580 (1975), where we quoted IB Larson’s Workmen’s Compensation Law § 41:31:
“* * * What set[s] occupational diseases apart from accidental injuries [is] both the fact that they can[not] honestly be said to be unexpected, since they [are] recognized as an inherent hazard of continued exposure to conditions of the particular employment, and the fact that they [are] gradual rather than sudden in onset. * * *”
In Valtinson v. SAIF, 56 Or App 184, 188, 641 P2d 598 (1982), we construed the phrase “sudden in onset” to mean occurring during a short, discrete period, rather than over a long period of time. Claimant’s condition meets this aspect of the injury test in that his back trouble coincided precisely with the traumatic jolting of the faulty loader. Claimant thus points to an identifiable event that caused his disability. The fact that his pain grew progressively worse over his six-week employment with Early does not make it “gradual in onset.”
Moreover, claimant’s condition meets the second aspect of the injury test in that it was unexpected. He had operated similar equipment for eight years prior to his employment with Early without any back trouble. It is more likely that his back condition was the result of the jolting of the loader at Early than “an inherent hazard from continued exposure” to the operation of front-end loaders, which the referee found usually involves bumping and bouncing.3
We conclude that claimant’s back strain was the result of an injury which occurred at Early, rather than an occupational disease. See Boise Cascade v. Starbuck, supra, 61 Or App at 641. The “last injurious exposure” rule is inapplicable. Early is responsible.
Reversed and remanded with instructions to reinstate the referee’s order.
Drake argues that, under Bracke v. Baza'r, 293 Or 239,646 P2d 1330 (1982), it is entitled to shift responsibility imposed under the “last injurious exposure” rule to Early by showing that claimant’s previous employment actually caused his “disease.” Bracke does not say that proof of actual causation is a defense to liability that may be asserted by the last employer. SAIF v. Luhrs, 63 Or App 78, 663 P2d 418 (1983). As stated in Fossum v. SAIF, 293 Or 252, 256, 646 P2d 1337 (1982), decided the same day as Bracke,
“In applying the last injurious exposure rule to claims for occupational diseases, however, the issue is not which employment actually caused the disease, but which employment involved conditions which could have caused it.” (Emphasis supplied.)
Bracke holds only that, when a claimant proves actual causation during a previous employment, that employer cannot use the “last injurious exposure” rule to assign responsibility to a later employer merely because the latter employment could have caused the disease.
Claimant said that, if he were working with the loader for eight hours, it would go forward or backward “probably 300 or 400 times.”
The concurrence would have us say that it is not unexpected that the operation of front-end loader with faulty transmission could cause disability and that, therefore, we recognize that claimant’s back trouble is an “inherent hazard of continued exposure to conditions of [his] particular employment.” To read this aspect of the “rule” as narrowly as the concurrence would have us do runs counter to our commonsensical notion of what institutes a traumatic injury. In that view, any disability caused by the faulty malfunctioning of equipment requiring repetitive operation would be treated as a disease. There is no authority for that.